Problem with emails that never arrive at destination

[klabacita]

Hi.

Guys, I would like you to share your experience with an issue I had, some times, some users
claim that some emails they send outside the company very important never arrive. This user has daily communication with the other end by email.

This is something that some times happens, we had before a issue with a company where I try to contact the sysadmin to troubleshoot this issue but I never receive answer.

Well my questions is, when you receive a claim like this one, how do you debug or troubleshoot or track issues with postfix/dovecot if exist?

I set up recipient_ sender_ to my email address to see all the communication with this user.

My DNS is working.

Any tip will be appreciated, thanks.

Postfix/dovecot.

 

[casdal]

The first step is to see if you can find the emails in your postfix mail log. If it's too hard to find, consider logging the email subject lines.

Now you can identify the message and confirm whether it's hitting postfix. You can see exactly if and how it fails by just grep'ing for the message ID.

 

[klabacita]

Right, I'm getting all the emails from this user and waiting to see when this happen again. Once I receive a complaint I will follow your instructions, thanks!