[Discuss] Mail loop advice?

[dbarrett at blazemonger.com (Daniel Barrett)]

Seeking advice on terminating an email loop.

A friend with an RCN account sent me an email with a very large
attachment. My ISP's server bounced it back to him, and RCN then
rebounced it. This produced an email loop that has been running for
about a week, bombarding my friend's account. My ISP (hostdime.com) is
responsive and has cleared the message from its mail queue several
times on my request, while my friend has no visibility into what RCN
is doing about it. (Their first-level helpdesk advised him to call
Microsoft for Outlook help. Their second level helpdesk performed
unknown tasks.)

Limitations: I don't have root access to my (shared) server: it's a
cpanel-based account. My ISP is not willing to change its global email
setup (say, to autodelete all email matching a pattern I provide) for
fear of impacting its other customers.

So I configured my cpanel spamassassin component to delete all email
from my friend (on my ISP's suggestion). This has not helped. I've
just configured it to delete all email from *@rcn.com and *@*.rcn.com;
however, I don't know if cpanel's spamassassin component kicks in
before or after the server's rule to bounce large attachments.

Grateful for ANY advice on solving this frustrating problem as a mere
client of the two service providers. (Anybody have a technical contact
at RCN?)

--
Dan Barrett
dbarrett at blazemonger.com