mautic.ERROR: [MAIL ERROR] Expected response code 354 but got code "503"

Your software
Mautic: 3.2.5, 3.3.1 and 3.3.2
PHP: 7.4
MySQL: 5.7
CentOS: 7.9
cPanel: 94.0.4
PHP-FPM: Activated
Service to send mail through: Other SMTP Server
SMTP encryption type: none
SMTP authentication mode: Plain
How should email be handled?: Send inmmediatly
Send test mail: Success!

Your problem
I have been using Mautic for several years now and it always worked fine, however, from version 3.2.5 to 3.3.1 as well as with 3.3.2, it is having problems to send the emails. I have tried all kind of combinations for SMTP or Sendmail and get different kind of errors for each one.

At this case, we are using SMTP without any encryption and the problem is that, when we execute:

sudo -u [USER] /usr/local/bin/ea-php74 /home/[USER]/public_html/bin/console mautic:campaigns:trigger --batch-limit=10 > /home/[USER]/public_html/var/logs/log-campaigns-trigger.log

It continuously shows the following errors:

[2021-03-24 19:14:02] mautic.ERROR: [MAIL ERROR] Expected response code 354 but got code "503", with message "503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 250 OK  << 550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries.  !! Expected response code 250/251/252 but got code "550", with message "550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries. " (code: 550) << 503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 250 OK  << 550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries.  !! Expected response code 250/251/252 but got code "550", with message "550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries. " (code: 550) << 503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA " (code: 503) !! Expected response code 354 but got code "503", with message "503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 250 OK  << 550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries.  !! Expected response code 250/251/252 but got code "550", with message "550-The mail server could not deliver mail to [EMAIL]. 550-The account or domain may not exist, they may be blacklisted, or missing 550 the proper dns entries. " (code: 550) << 503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503-All RCPT commands were rejected with this error: 503-The mail server could not deliver mail to [EMAIL]. 503-The account or domain may not exist, they may be blacklisted, or missing 503-the proper dns entries. 503 Valid RCPT command must precede DATA " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 354 but got code \"503\", with message \"503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 250 OK\r\n\n<< 550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\n!! Expected response code 250/251/252 but got code \"550\", with message \"550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\" (code: 550)\n<< 503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 250 OK\r\n\n<< 550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\n!! Expected response code 250/251/252 but got code \"550\", with message \"550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\" (code: 550)\n<< 503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\" (code: 503)\n!! Expected response code 354 but got code \"503\", with message \"503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a3a600858100349@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 250 OK\r\n\n<< 550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\n!! Expected response code 250/251/252 but got code \"550\", with message \"550-The mail server could not deliver mail to [EMAIL].\r\n550-The account or domain may not exist, they may be blacklisted, or missing\r\n550 the proper dns entries.\r\n\" (code: 550)\n<< 503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503-All RCPT commands were rejected with this error:\r\n503-The mail server could not deliver mail to [EMAIL].\r\n503-The account or domain may not exist, they may be blacklisted, or missing\r\n503-the proper dns entries.\r\n503 Valid RCPT command must precede DATA\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:02] mautic.ERROR: [MAIL ERROR] Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) !! Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7a8c725173671268@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:02] mautic.ERROR: [MAIL ERROR] Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503)\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aa170d713362487@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:02] mautic.ERROR: [MAIL ERROR] Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) !! Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7aba364244669437@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:12] mautic.ERROR: [MAIL ERROR] Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " Log data: >> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 451 Temporary local problem - please try later  !! Expected response code 250/251/252 but got code "451", with message "451 Temporary local problem - please try later " (code: 451) << 503 Valid RCPT command must precede DATA  !! Expected response code 354 but got code "503", with message "503 Valid RCPT command must precede DATA " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503)\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f7ac96a0434388168@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 451 Temporary local problem - please try later\r\n\n!! Expected response code 250/251/252 but got code \"451\", with message \"451 Temporary local problem - please try later\r\n\" (code: 451)\n<< 503 Valid RCPT command must precede DATA\r\n\n!! Expected response code 354 but got code \"503\", with message \"503 Valid RCPT command must precede DATA\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:12] mautic.ERROR: [MAIL ERROR] Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) Log data: >> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) !! Expected response code 250 but got code "503", with message "503 sender already given " Log data: >> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  << 503 sender already given  !! Expected response code 250 but got code "503", with message "503 sender already given " (code: 503) (code: 503) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 503): Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503)\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\"\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f84ba7cd739997039@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n<< 503 sender already given\r\n\n!! Expected response code 250 but got code \"503\", with message \"503 sender already given\r\n\" (code: 503) (code: 503) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:13] mautic.ERROR: [MAIL ERROR] Expected response code 354 but got an empty response Log data: >> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250/251/252 but got an empty response (code: 0) !! Expected response code 354 but got an empty response (code: 0) Log data: >> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250/251/252 but got an empty response (code: 0) !! Expected response code 354 but got an empty response (code: 0) !! Expected response code 354 but got an empty response Log data: >> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250/251/252 but got an empty response (code: 0) !! Expected response code 354 but got an empty response (code: 0) (code: 0) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 0): Expected response code 354 but got an empty response\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250/251/252 but got an empty response (code: 0)\n!! Expected response code 354 but got an empty response (code: 0)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250/251/252 but got an empty response (code: 0)\n!! Expected response code 354 but got an empty response (code: 0)\n!! Expected response code 354 but got an empty response\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85080a7607392040@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250/251/252 but got an empty response (code: 0)\n!! Expected response code 354 but got an empty response (code: 0) (code: 0) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []
[2021-03-24 19:14:13] mautic.ERROR: [MAIL ERROR] Expected response code 250 but got an empty response Log data: >> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250 but got an empty response (code: 0) Log data: >> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250 but got an empty response (code: 0) !! Expected response code 250 but got an empty response Log data: >> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>  >> RCPT TO:<[EMAIL]>  >> DATA  !! Expected response code 250 but got an empty response (code: 0) (code: 0) (send); [EMAIL] {"exception":"[object] (Swift_TransportException(code: 0): Expected response code 250 but got an empty response\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250 but got an empty response (code: 0)\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250 but got an empty response (code: 0)\n!! Expected response code 250 but got an empty response\nLog data:\n>> MAIL FROM:<envios+bounce_605b8f85143b2354587318@[DOMAIN]>\r\n\n>> RCPT TO:<[EMAIL]>\r\n\n>> DATA\r\n\n!! Expected response code 250 but got an empty response (code: 0) (code: 0) at /home/[UDER]/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124)"} []

Steps I have tried to fix the problem:
I have changed to SMTP multiple configurations, tried several values for --bath-limit, aumeted the php allow memory upto 1.5GB (1024MB normally), etc.

Please do not post duplicate messages across multiple channels. This is spamming and is not in line with our Code of Conduct.

I have deleted your Slack message and merged your other post here - if is is the same info please delete the duplication.

Linking the Github issue that you also created so that there is visibility:

which is a duplicate of an existing issue:

Sorry @rcheesley I was confused about how to report it as the bug/problem errors are different based on the email method (SMTP with/without SSL and Sendmail)

Posting the same thing multiple times in multiple places is never the right way to go :slight_smile:

Hopefully we can get someone to take a look at the issue - you can choose to add a bounty to the issue on Github if you are able which may possibly help to have it looked at sooner if a developer is able pick it up.

Hi there! We also have this issue, is this issue being worked on by someone? Thanks for replying!

Don’t know if this has been tackled, but I am experiencing the exact same issue.
I opened a thread here