Issue Sending Emails To or Forwarding To Gmail address
We have purchased a GoDaddy VPS (managed) for our company. There's only one account in it.
Lately, the last 4 weeks or so, we've been experiencing issues when sending emails to Gmail addresses or trying to forward to Gmail addresses.
First, we'd set up forwarders for some email accounts through Cpanel e.g. someone@ourcomanydomain forward to firstname.lastname@example.org. It worked fine but over the last few weeks, emails have been bouncing. Mostly, the error message has been the same - "Reason: There was an error while attempting to deliver your message with (Subject: 'whatever_subject') to 'email@example.com'. It has been in queue too long, and will not attempt delivery again."
I removed all forwarders and setup Gmail accounts to check for email using POP3. However, some emails still bounce (with the same error message above) when sending emails to Gmail addresses using our work emails using Gmail's "Send email as" feature. Personally, I use Microsoft Outlook and haven't experienced as many bounces (still happens once in a while) as those using their Gmail accounts.
I don't know what this queue is, or where it's located. When I log into WHM and go to Mail Queue Manager, I don't see anything; it's always empty.
Note that our VPS (WHM/Cpanel) is up to date. I check for updates every day.
Tried contacting GoDaddy support but they couldn't find any issues. If anyone here can offer a solution, I'd be very happy. If not, we'll just migrate to another hosting provider.