Error to add emails to be managed by gmail

Hello, my people, I’ve done all the tests the mail server is working I send and receive emails without problem in thunderbird, but when I went to add the email to I can receive and send by gmail I get this error

Error returned by the server: “Missing + OK response upon connecting to the server: * OK [CAPABILITY IMAP4rev1 LITERAL + SASL-IR LOGIN-REFERRALS ID ENABLE IDLE STARTTLS AUTH = PLAIN AUTH = LOGIN] Dovecot (Ubuntu) ready.”

to be honest, I did not understand anything

here is the result in my mail tester

I believe I’m doing my homework, but this mistake I do not have a direction to solve

Can someone help me with this problem that this simple mortal can not :slight_smile: