eM client and Postfix say email with attachment has been sent but it never arrives.

eM client running on Win10 sends emails from Postfix running on RPi unless there’s an attachment. Then it says it has sent it but it never arrives.

Is the message arriving at the MTA?

Hi Gary. I’m afraid I don’t know what an MTA is.

That would be the PostFix server. Is it receiving the message from eM Client?

I’ve just checked a plain text message and that’s not arriving at the recipients mail box either. Whether it’s getting to the MTA I’ve no way of knowing (at least not within my capability). Is there an easy way to check?

Because the MTA is a Raspberry Pi, I assumed it was some project you setup. If you did, you must have some way to manage it. I think that is where the problem is. Did you try connecting to a normal IMAP server to see if the messages are being sent OK?

You can check in eM Client if there are any errors. Go to Menu > Tools > Operations, and look in the log for any errors. You might also right-click on Smart Folders and select Outbox. Now go to that folder and see if the missing messages are still there waiting to be uploaded to the MTA.

No errors in log, Gary! All emails end up in ‘Sent’. There’s nothing marked ‘smart folders’. I’m not sure what right clicking on ‘Outbox’ should do but there are no emails in that directory.

Seems everything is running as it should in eM Client then. I think the problem is with your MTA. 

Fair comment. Any ideas how to get Postfix help?

If you go to their website, there is a link to mailing lists. That is a good place to ask questions.