"error closing connection to SMTP server" after working for 7 months

Hi,

I've been having kapacitor email my team for certain alert for 7 months, and it's been working well up until yesterday. I'm getting the following error, and I have no idea what could be happening:

**lvl=error msg="error closing connection to SMTP server" service=smtp err="x509: certificate is not valid for any names, but wanted to match xxxxx.com"**

I've tested the smtp server using telnet, and nothing is wrong with that. Is this an issue with kapacitor - and if so, what could it be - or is it an external error? I have log alerts set up for all of the alerts, and that part is working just fine.

Any help would be greatly appreciated, thanks!

The report identifies an SMTP certificate-validation error but names no source file, test, or entry point. Start by tracing Kapacitor's SMTP handling for the reported x509 error and compare it with the stated telnet result. Done means establishing whether the failure is in Kapacitor or the external SMTP certificate and documenting a reproducible fix or diagnosis.

Written by the indexing model from the issue text.