[Koha] gmail account in koha 3.22.21

[George Mikuchadze]

Dear colleagues,
I have Koha v3.22.21 (the last one in the 3rd branch) and I have a Gmail
account to send overdue notes to patrons.
Ubuntu 16.04 was OS for the koha server (till the end of Apr 2021, and now
I upgraded to Ubuntu v 18.04). I used the "CONFIGURE.gmail" document to
configure xinetd service to send overdue messages to koha OPAC users
through my Gmail account. But there was some trouble(I don't know what) and
koha didn't send any overdue notes since Apr 2020. I tried to use postfix
for the purpose but without success. Can anybody give me advice on this
issue?

Best regards
George Mikuchadze