The new Lugdunum patched servers p75+ have a credit system to judge the clients behaviour. Each action like connecting, searching, asking for sources etc. costs credit points.If they are all used up, the server disconnects and sends a warning that this client is blacklisted.
This especially is a problem when downloading more than ~30 files as the source asking for all this downloads will cost that many credits, banning the client. eMule v.30a+ takes care of this problem.
Additional information on this topic on SilentBob's web site.

Last update: Monk