My configuration is as follows:
vi /etc/gitea/app.ini
[mailer]
PASSWD = mypasswd
ENABLED = true
FROM = mymail@domain.com
USER = mymail@domain.com
HOST = smtp.domain.com:465
MAILER_TYPE = smtp
IS_TLS_ENABLED = true
I used the links below:
https://forum.gitea.com/t/solved-problems-configuring-gmail/2003
https://github.com/go-gitea/gitea/issues/10971