I having a 12.04 Ubuntu with LAMP stack droplet and have configured iRedMail which comes with Postfix.
After the setup I am able to receive mails and also send mails to gmail and yahoo mail servers. However, with the other domains its giving me the following error :
Diagnostic-Code: smtp; 550-Verification failed for
550-No Such User Here 550 Sender verify failed
These answers are provided by our Community. If you find them useful, show some love by clicking the heart.
If you run into issues leave a comment, or add your own answer to help others.