500 Internal Server Error when Trying to Send Single Email or Test Email (Using Amazon SES)

Your software
My Mautic version is: v2.16.0
My PHP version is: 7.2

Your problem
My problem is: Whenever I click to send a direct email or a test email, I’m getting this error:

These errors are showing in the log:

[2020-03-11 23:13:30] mautic.CRITICAL: Uncaught PHP Exception Swift_RfcComplianceException: "Address set in PathHeader does not comply with addr-spec of RFC 2822." at /home/crm.regh.io/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/PathHeader.php line 138 {"exception":"[object] (Swift_RfcComplianceException(code: 0): Address set in PathHeader does not comply with addr-spec of RFC 2822. at /home/crm.regh.io/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/PathHeader.php:138)"} []
[2020-03-11 23:23:58] mautic.CRITICAL: Uncaught PHP Exception Swift_RfcComplianceException: "Address set in PathHeader does not comply with addr-spec of RFC 2822." at /home/crm.regh.io/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/PathHeader.php line 138 {"exception":"[object] (Swift_RfcComplianceException(code: 0): Address set in PathHeader does not comply with addr-spec of RFC 2822. at /home/crm.regh.io/public_html/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Mime/Headers/PathHeader.php:138)"} []

I believe the last error is the most relevant one to this issue.

Steps I have tried to fix the problem:
I’ve cleared the cache and updated schema (no idea if those are relevant to this.)

I did not always have this issue… I got this issue after trying to fix my bounce management and sent a bunch of emails to Amazon’s bounce management thing. I feel like it was after that that this started.

Anyone have any ideas? Hoping to get some help or direction on this

I have the same problem: Error 500 sending email