XF 1.5 Can not authenticate to POP3 server: [AUTH]

[Phantro]

I have so many erros minute after minute over my forum, ill pass here that 2 screenshots from erros:

Server Error Log
Error Info
ErrorException: Unknown: Retrying PLAIN authentication after [AUTH] Authentication failed. (errflg=1) - Unknown:0
Generated By: Unknown Account, 37 minutes ago
Stack Trace
#0 [internal function]: XenForo_Application::handlePhpError(8, 'Unknown: Retryi...', 'Unknown', 0, Array)
#1 {main}
Request State
array(3) {
  ["url"] => string(40) "https://www.MYDOMAIN.com/forum/deferred.php"
  ["_GET"] => array(0) {
  }
  ["_POST"] => array(4) {
    ["_xfRequestUri"] => string(7) "/forum/"
    ["_xfNoRedirect"] => string(1) "1"
    ["_xfToken"] => string(8) "********"
    ["_xfResponseType"] => string(4) "json"
  }
}

Server Error Log
Error Info
ErrorException: Unknown: Can not authenticate to POP3 server: [AUTH] Authentication failed. (errflg=2) - Unknown:0
Generated By: Unknown Account, 38 minutes ago
Stack Trace
#0 [internal function]: XenForo_Application::handlePhpError(8, 'Unknown: Can no...', 'Unknown', 0, Array)
#1 {main}
Request State
array(3) {
  ["url"] => string(40) "https://www.MYDOMAIN.com/forum/deferred.php"
  ["_GET"] => array(0) {
  }
  ["_POST"] => array(4) {
    ["_xfRequestUri"] => string(7) "/forum/"
    ["_xfNoRedirect"] => string(1) "1"
    ["_xfToken"] => string(8) "********"
    ["_xfResponseType"] => string(4) "json"
  }
}

I already tried so many things, tried to disable emails, tried to change configurations, already have confirmed login and passwords... but no way, error logs dont stop it!

 

[AndyB]

I suggest using the default email transport method.