I use XEAMS using a custom domain that sends mail via gmail as smtp smarthost (using a gmail account and token password). After several months

sending mail did not work anymore, i discovered that now my server was sending directly emails without using the smarthost causing mails to fail and even in the end it got blocked on spamhouse.

After using the test button on the smarthost section XEAMS warned the token / password was expired ! After re-entering the same password it worked again.

XEAMS does not warn about this, so be aware !