Suddenly my SMTP is blocked

Cant send emails anymore.
Both http and https smtp sites have been added as exceptions but no difference.

Jim

More details might help. What email server? Any recent changes or updates?
What version of Avast are you using? Any other security related programs?

smtp.puretelecom.ie using Thunderbird mail on port 25.
Avast has blocked this because the signatories of the certificate has expired.
But i have been using this for past 2yrs.

When i have smtp addresses entered as exceptions Avast should allow them open, Right??