MyBB Community Forums

Full Version: Unknown sender problem in email notifications
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
It has been 2-3 months since I saw this problem in my new MyBB install in two different forums but which are duplicate. I've tried to debug and correct it but to no avail.

Problem: In any email reply notification sender is shown as "Unknown sender". It works fine in case of user registration email. Even sending email/PM from forum has this problem.

I'm attaching required files:
  • Unknown sender as seen in gmail
  • (in zip file) mail header of unknown sender
  • (in zip file) mail settings
  • (in zip file) mybb configuration settings


I've installed a couple of trustable plugins like no links allowed, google seo etc. I've also compared full mybb original file with that of my installation files. Although some files in my installation were added due to plugins but only 3 files were little different, but none changing mail parameters.
Mine is on Hostgator Linux shared hosting with two other PHPBB forums with no problems whatsoever including many other Joomla and Drupal sites.
Why does it work fine in case of user registration mail?
I don't know how to debug and correct it. Some help will be appreciated.