I run a number of sites which are hosted on a standard Linux server, but I recently moved the newsletter management system to a separate Cobalt RAQ 2 server to decrease the load on the main one.
I use that server to send out the site's daily newsletter, but the problem is that for some reason the server tends to choke after sending about 14000-15000 messages. It doesn't crash, but it just stops sending. The problem is not with the script as on the old server it could handle the whole list.

Any ideas on what's wrong? Does Cobalt have some kind of an email limitation?

I tried to email Sun, but they don't bother to reply.