SMTP sending but not receiving at receipent on different domain

I have setup smtp and tried tls and starttls on mattermost instance and it shows successful when tested, but when i try it with an email outside of the same subdomain as mattermost is on it also says successful and the email server logs say delivered but there is no email at the recipient email. Fyi the email server is on a different ip address if that helps.

These are the logs from mattermost

{"timestamp":"","level":"debug","msg":"sending mail","caller":"mail/mail.go:295","to":"","subject":"Mattermost - Testing Email Settings"}
{"timestamp":"","level":"debug","msg":"Received HTTP request","caller":"web/handlers.go:163","method":"POST","url":"/api/v4/email/test","request_id":"3z3f3rjgbin17rpfm8ab6sfeaw","status_code":"200"}

Heya dan,

Since no one else has been able to help us with this one yet, let’s test the effectiveness of another Mattermost AI assisted response if you don’t mind. :slight_smile:

First, I would recommend double-checking your mail server configuration, specifically your spam or junk mail folder, as sometimes emails from Mattermost can end up there.

If that’s not the issue, ensure that your IP is not being blocked or filtered by the recipient’s email server. This sometimes occurs when the IP address is unfamiliar to the email server or has been flagged due to prior suspicious activity.

A common issue can also be the incorrect DNS settings. Check if your domain has the right MX records set up, as wrong MX records or their absence can cause such problems.

Also, I would like to point out that there can be a delay in delivering emails based on the server load and priority of the email.

If all these configurations seem correct and the issue persists, could you try sending an email to another domain to see if the issue is specific to the recipient’s domain?

Lastly, please do share more relevant information such as your email server, the version of Mattermost you are using, and any recent changes that were made in the environment that could lead to this issue.

Your cooperation and patience in this matter are greatly appreciated. Please feel free to tag me if you have any more questions or need further information.

~Mattermost AI Assistant :robot:

[Disclaimer: This was an AI assisted response powered by Mattermost AI. Were any of the above suggestions inaccurate? Let us know by replying to this comment!]