Admin Email Notification Sending Failed - PHPMailer Exception - SMTP Error: Could not connect to SMTP host. (Subject: WHMCS Domain Synchronisation Cron Report)

[WeGoHostU Web Services]

I am having this issue on my server.

Admin Email Notification Sending Failed - PHPMailer Exception - SMTP Error: Could not connect to SMTP host. (Subject: WHMCS Domain Synchronisation Cron Report)

[ptomter]

I also got this now after upgrading to latest version of WHMCS yesterday. Did  you find any solution to this @WeGoHostU Web Services

[WHMCS ChrisD]

Hello @ptomter

What are you using for email PHP Mail or SMTP?  Who is your email provider if SMTP and what settings are you using?

[ptomter]

I use SMTP, and Microsoft 365 solution. I downgraded / put a earlier backup in place and now everything works again so I have to figure out this later when planning to upgrade to latest WHM version.

[carlswart]

When I switched to SMTP and enabled SSL/TLS I had to make sure the SMTP Host and the common name in the SSL certificate matched. When it did not match, I had errors. Perhaps test SMTP without SSL/TLS on. If that works, then you were experiencing the same problem as I had.

[Maly]

can anybody give a hand

As i have the same issue but it happens randomly . on the other hand, ssl/tls protocols are already disabled on both relay machine and WHMCS. 

[NicolasL]

Glad to see I am not alone. I am the same issue since I updated from WHMCS 7.9 to 8.1.3. My System logs is flooded every hours with this error :

Quote

Admin Email Notification Sending Failed - Mailer Exception - Email Sending Failed: SMTP connect() failed. https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting (Subject: WHMCS Domain Synchronisation Cron Report)

For now, WHMCS Support is not helpful about this report, even after many go and back. 

My SMTP configuration is correct, as I am receiving many other emails and admin notifications. 

For me, there is obviously a little glitch in this WHMCS version. I just would like to hear from WHMCS that this is a known issue and that they escalade the report to the relevant team for the next update, and that's it ! I am satisfied. But I keep hearing that the issue probably comes from my side despite I didn't have the problem with 7.9, and I keep hearing that the support cannot reproduce the supposed random issue, despite it happen (almost) every hours at the exact same time. 

It's tiring.