I see. Maybe that's because mailtrain adds unsubscribe headers in the email header etc. I don't really know of any other bulk mailer software. Are you able to contact the support of turbo mailer and ask them if they support STARTLS at all?

@girish said in Allow SSL /TLS in email outbound SMTP settings:

Are you hosting a custom domain on mailbox.org or do you have a @mailbox.org address? If it's the latter, mailbox is then not really an email relay. Generally, email relays are able to forward all addresses of a domain i.e anything@cloudrondomain.tld.

BTW I figured out how to use mailbox.org as a relay: https://kb.mailbox.org/display/MBOKBEN/Using+e-mail+addresses+of+your+domain
I obviously skipped the part setting the mx values but otherwise it’s been working well the past weeks.

thanks for the explanations. I have already contacted digital ocean requesting the release of port 25.

at first, strangely, they claimed that there is no output block on port 25 (although I did the test with the command 'telnet' in the cli).