[BlueOnyx:17400] strange delay from mailman

[Barry Mishkind]

A very odd issue has arisen, and perhaps someone knows of a solution.

In the interests of spam prevention, I was advised to turn on greylisting.
(The server is using BX 5106R   Mailman V 2.1.9)

While it appears that greylisting is working, a side-effect has occurred, which
turning greylisting off did not fix.

Specifically, email from one of the mailing lists on the site will post immediately
(as verified by the archive ../pipermail/<listname>

But .. the same post is delayed for one to two hours in sending the copy to
the local address here on the server. If I subscribe directly to my ISP address,
it comes right in, but to the main alias on the server, it seems to take
hours to return.

Any ideas where to look for this one?

Thanks!