SMTP stopped working

Hi. SMTP does not work on all mailboxes. Letters remain in the sent. What appears: SSLHandshakeException Connection closed by peer (gmail)
SMTP response is 0 length (disroot). All settings are correct.

So that we have some basic information to work from, could you please provide … android version, k9 release and all the configuration details on the relevant (gmail) sending mail/outgoing server screen.

Also, though likely not directly relevant given that error message you report, have you set up and are you using app-passwords with this gmail account?

Annex version 5.807. Android 7.1.2. Password applications do not use.
SMTP Gmail Settings:
port 465.
Authorization Da
Normal password
Do not use the Customer Certificate

What is the “security” setting – found just above the port number?

If I read things correctly, if you don’t switch to using app passwords by the end of May you won’t be able to use gmail with K9.