user mailman was not found

[sehh]

We recently noticed that our /var/log/exim_panic was filling up with the following error:

Exim configuration error in line 1217 of /etc/exim.conf: user mailman was not found

Line 1217 contains:

    user = mailman

and finally, mailman user does exist as seen below:

mailman:x:32001:32001::/usr/local/cpanel/3rdparty/mailman:/bin/bash

any ideas please?

PS:
we have disabled mailing list support from WHM since we don't need it and its one of the worst things to run on a VPS, it takes too much memory and cpu to run it.