From eScan Wiki
MailScan - FAQ's
Q. Possible looping error shown in MailScan for SMTP.
This happens when you send an email to a domain, and the MX record for that domain is listed as 127.0.0.1.
For example, if you send mail to firstname.lastname@example.org, SMTP will show you this error message.
To verify this,
If you notice, the mail exchanger (mx) is listed as 127.0.0.1. Hence the looping error is shown by MS for SMTP.
Download latest SMTP.EXE (version 188.8.131.52 and above) (click here to download the SMTP.EXE) and overwrite the old SMTP.EXE (in %MailScan% folder) with the new one. In this new version, the error message is NOT shown and the mail will be bounced back to the sender.
Email us your feedback to email@example.com