Error: Unable to send message(s) in Outbox

Error: Unable to send message(s) in Outbox

Hi,

I have also sent this message to the Zoho mail support address. I'm posting on the forum in case anyone else has the same problem.

After sending an email I get the messages ' You have unsent message(s) in Outbox' and 'Unable to send message(s) in Outbox'. The mail remains stuck in the outbox. When I click on the red exclamation mark I see this additional error message -

'Reason:sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target'

I have no idea what this means. The problem only occurs when I try to send mail using my alternative 'Send as' address like example@mail.com . It doesn't occur if I send using my main zoho address. The 'Send as' address has been properly validated. I have used it with Zoho for several years.

At present I am unable to send any mail using my alternative address.

Thanks, Bob