XF 2.1 Mass emails not sending

[SuperMonis]

Trying to send an important email to around 11,000 registered members but getting an error and no one is recieving the emails:

 

[Ozzy47]

See this guide: https://xenforo.com/community/resources/email-troubleshooting-guide.5086/

 

[SuperMonis]

See this guide: https://xenforo.com/community/resources/email-troubleshooting-guide.5086/

Didn't really help, emails are being sent to users when they register. I'm only getting this issue when using the mass email option.