spent a lot of time trying to configure mail for sssihl.edu.in with 1and1.com - the user interface is somewhat restrictive. Have configured the mx record to point to the records given by
host -t MX sssihl.edu.in ns41.1and1.com
(also host -a sssihl.edu.in ns41.1and1.com)
so the mail servers are mx00.1and1.com and mx01. Pointing from Plesk to these mail servers, still mails to the account I created are bouncing with 550 won't relay to firstname.lastname@example.org
Maybe the mail servers need time?