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Full Version: SMTP Error - RTCP TO command
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Hey MyBB Community,

i am using MyBB for my small little forum now for about 1 year. Everything works perfectly since then. I was using phpmail with a smtp relay from gmail to send users authentication emails, but now i build my own mailserver with postfix and dovecot ( / and i connected my Phone (GS8+), Outlook, Thunderbird without any problems. 

Now i wanted to switch my forum from phpmail to smtp, so user receive emails from "[email protected]" instead of "root - [email protected]". When i register after the settings changed to SMTP i get the error message: 

The mail server does not understand the RCPT TO command. Reason: 553 5.7.1 <[privateadminmail]>: Sender address rejected: not owned by user [email protected]

It actually cant be my mailservers fault, because it works on multiple Platforms in different networks. I think my mailserver needs a sender email or something.

Any ideas?

Thank you in advance!
I think you are using the wrong username. Are you sure that the email address is the same as the username on your mailserver? Could not be.
Thank you for the quick reply!

I tripple checked the login credentials (writing in Notepad and copy/paste), there is no Problem. I think MyBB wants to login via [email protected], what is ok, but send with [email protected] what the Mailserver refuses because he has no [email protected] in the user database..
You need to change the administrator email in ACP > Configuration > Site Details > Admin Email

You can also optionally change the Return Email, Contact Email and Contact Us Link settings too.
Thank you very much!

The Problem is solved! Everything works fine now!!