[SOLVED] Swift mailer not sending embedded images

Mautic 4.4.4
PHP 8.0.20
MariaDB 10.5.16

Updating/Installing Errors
I am installing via command line.

These errors are showing in the installer
None

These errors are showing in the Mautic log :
[2022-12-20 11:30:37] mautic.ERROR: [MAIL ERROR] Connection to tcp://mail1.mhp.es:25 Timed Out Log data: ++ Starting Swift_Transport_EsmtpTransport << 220 mail1.mhp.es >> EHLO [192.168.200.117] << 250-mail1.mhp.es 250-PIPELINING 250-SIZE 1258291200 250-VRFY 250-ETRN 250-STARTTLS 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN >> STARTTLS << 220 2.0.0 Ready to start TLS >> EHLO [192.168.200.117] << 250-mail1.mhp.es 250-PIPELINING 250-SIZE 1258291200 250-VRFY 250-ETRN 250-AUTH PLAIN LOGIN 250-AUTH=PLAIN LOGIN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN >> AUTH PLAIN *************************************** << 235 2.7.0 Authentication successful ++ Swift_Transport_EsmtpTransport started >> MAIL FROM:info@server.es >> RCPT TO:randomuser@gmail.com >> DATA << 250 2.1.0 Ok << 250 2.1.5 Ok << 354 End data with . >> . !! Connection to tcp://mail.server.es:25 Timed Out (code: 0) (send); randomuser@gmail.com {“exception”:“[object] (Swift_TransportException(code: 0): Connection to tcp://mail.server.es:25 Timed Out\nLog data:\n++ Starting Swift_Transport_EsmtpTransport\n<< 220 mail1.mhp.es\r\n\n>> EHLO [192.168.200.117]\r\n\n<< 250-mail.server.es\r\n250-PIPELINING\r\n250-SIZE 1258291200\r\n250-VRFY\r\n250-ETRN\r\n250-STARTTLS\r\n250-ENHANCEDSTATUSCODES\r\n250-8BITMIME\r\n250 DSN\r\n\n>> STARTTLS\r\n\n<< 220 2.0.0 Ready to start TLS\r\n\n>> EHLO [192.168.200.117]\r\n\n<< 250-mail.server.es\r\n250-PIPELINING\r\n250-SIZE 1258291200\r\n250-VRFY\r\n250-ETRN\r\n250-AUTH PLAIN LOGIN\r\n250-AUTH=PLAIN LOGIN\r\n250-ENHANCEDSTATUSCODES\r\n250-8BITMIME\r\n250 DSN\r\n\n>> AUTH PLAIN ********************************************\r\n\n<< 235 2.7.0 Authentication successful\r\n\n++ Swift_Transport_EsmtpTransport started\n>> MAIL FROM:info@server.es\r\n\n>> RCPT TO:randomuser@gmail.com\r\n\n>> DATA\r\n\n<< 250 2.1.0 Ok\r\n\n<< 250 2.1.5 Ok\r\n\n<< 354 End data with .\r\n\n>> \r\n.\r\n\n!! Connection to tcp://mail.server.es:25 Timed Out (code: 0) at /var/www/html/mautic/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Plugins/LoggerPlugin.php:124, Swift_IoException(code: 0): Connection to tcp://mail.server.es:25 Timed Out at /var/www/html/mautic/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php:166)”} {“hostname”:“emm”,“pid”:364739}

I get this error when I try to send medium sized emails (with two images, for example), small sized emails (text only or one small image at most) are sent ok. The Postfix SMTP server has a very large limit for outgoing messages and the “medium sized” emails area 10% size of maximum SMTP message size. Any ideas? Are there any size or content limitations for SMTP transport inside mautic?

Steps I have tried to fix the problem :

  • Changing SMTP account, changing port (25, 587, et cetera).
  • I have access to Postfix logs, when send is ok I get these logs:

mail postfix/smtpd[7517]: connect from xxx.xxx.xxx.xxx
mail postfix/smtpd[7517]: Anonymous TLS connection established from xxx.xxx.xxx.xxx: TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)
mail postfix/smtpd[7517]: D923840BEA: client=xxx.xxx.xxx.xxx, sasl_method=PLAIN, sasl_username=info
mail postfix/smtpd[7517]: disconnect from xxx.xxx.xxx.xxx

But when I try to send the medium sized emails, the last line “disconnect” is not shown in mail log.

The problem was solved:

The Postfix al STMP server uses Amazon SES as SMTP backend. I “shortcircuited” the Postfix configuring Mautic with an Amazon SES SMTP server and all goes ok!

I think it is a problem with Swift Mailer <–> Postfix interaction.

Thank you!