account IMAP cerified no work in sending

Good morning,

I am a loyal customer of yours and I am a lawyer. I need your help.

Suddenly my certified email account (PEC) gives me an error when sending emails. the problem is below: the server is not responding.
All the parameters are correct (sendm.cert.legalmail.it - ​​potra 465) but sometimes it doesn’t send, other times it sends the PEC repeatedly even 10 I guess because I can’t save the email in the sent mail. It remains “stuck” in the outgoing mail. I attach a screenshot of errore, thanks.

The certified e-mail address is: [email protected]

Tank you

Alfredo Crescenzo