ERROR_CODE :554 Undelivered Mail Returned to Sender

ERROR_CODE :554 Undelivered Mail Returned to Sender

Hi Zoho,

One of my users who has been using without a problem for around a year has now reported quite frequently that mail is getting returned when sending mail to people he's sent many times before.

The most recent of these bounces is as follows;

  1. xxxx@flexicruise.com Error, ERROR_CODE :554, ERROR_CODE :5.7.1 Mail (id-41560-64384) appears to be unsolicited - Totalscore(71) over limit(50) - resend with the code 6e1y2e2e appended to subject and ask to have your email whitelisted (the code 6e1y2e2e changes each 24 hours).
It certainly wasn't unsolicited email, it was actually a reply to someone elses (who he knows, and emails regularly, including with other staff CC'd).

Any ideas why its doing this?

Cheers