Outlook 365 suddenly can't connect to SMTP

GoWilkes

Well-Known Member
Sep 26, 2006
611
24
168
cPanel Access Level
Root Administrator
I'm having an odd issue, and after eliminating variables I think that the issue HAS to be with Outlook? But I'm not sure if it has something to do with a connection between Outlook and the server.

I have 2 computers on the same local network, both using Outlook 365 and set up the same way. For incoming email we IMAP to Gmail, and outgoing goes through two email addresses on my server. I also have both Gmail accounts set up to send emails through the same email address on my server.

My email is working fine, no errors.

The other computer's Outlook is throwing an error that it can't connect to SMTP. It was working fine yesterday, but has been throwing this error all day.

Logging in to Gmail.com on that same computer, I was able to send email. I can also ping and tracert to mail.mydomain.com (the same as the SMTP in Outlook), so it's not an issue of connectivity.

I turned off CSF and cPHulk on the server, and turned off Windows Defender on the problem computer... no help. I also tried opening Outlook in safe mode, but it still had the same error.

But what's weird is that the mobile device that uses that same SMTP is ALSO throwing an error. So it worked on Gmail.com, but not Outlook or her mobile device. So maybe it's NOT Outlook?

Any other thoughts? Did something change overnight, either with cPanel or Outlook? I'm running out of ideas :-O
 

GoWilkes

Well-Known Member
Sep 26, 2006
611
24
168
cPanel Access Level
Root Administrator
Update: it's definitely a server issue. I discovered today that emails being sent to ME are bouncing, and I'm not able to send, either. I'm receiving emails sent through the server, but not emails sent from other people.

I turned off Greylist, cPHulk, and CSF, then tried sending an email from my unrelated Gmail account to an email on the server that forwards to a different Gmail, and also tried sending it to a POP account on the server that doesn't forward anywhere. Neither arrived.
 

GoWilkes

Well-Known Member
Sep 26, 2006
611
24
168
cPanel Access Level
Root Administrator
Hopefully a final update: I saw that I was low on server storage (like 99.1% full), so I started deleting some things. I had 4G available so I don't THINK that would be relevant? But maybe.

While it was deleting, I restarted Exim.

And then I started getting in emails. So I don't know which one of those "fixed" it, but it appears to be working now. So no further help needed :)