Unable to send email from docker image

Describe the bug

When trying to send email (password reset) from the docker image. The container is unable to login to the SMTP server

Relevant logs and/or screenshots

Trying to send an email from sendmail in verbose mode:

sendmail: recv:'220 mail.example.com ESMTP Postfix (Debian/GNU)'
sendmail: send:'EHLO 211911ddb569'
sendmail: recv:'250-mail.example.com'
sendmail: recv:'250-PIPELINING'
sendmail: recv:'250-SIZE 10240000'
sendmail: recv:'250-VRFY'
sendmail: recv:'250-ETRN'
sendmail: recv:'250-STARTTLS'
sendmail: recv:'250-ENHANCEDSTATUSCODES'
sendmail: recv:'250-8BITMIME'
sendmail: recv:'250-DSN'
sendmail: recv:'250 SMTPUTF8'
sendmail: send:'AUTH PLAIN'
sendmail: recv:'503 5.5.1 Error: authentication not enabled'
sendmail: AUTH PLAIN failed

Context

Castopod in official docker images (last stable).

Possible fixes

Try to send a different EHLO ? https://github.com/codeigniter4/CodeIgniter4/blob/master/system/Email/Email.php#L1903 Might need to change the container hostname in the nginx conf fastcgi_param SERVER_NAME $host;