I setup exim in order to send messages via a smarthost when the recipient domain is in a specific list, otherwise the delivery is direct via remote SMTP.
Once in a while some remote smtp server refuses the connection with error messages like 554 5.7.1 Service unavailable; Client host [XX.YY.ZZ.KK] blocked using *.zen.dq.spamhaus.net and the submitter gets the error message of the failed delivery.
I would like to let exim automatically use the smarthost when error from remote smtp is 5.7.1. Is this possible? Thank you very much