Too many open files

[Alex]

Hi,

I'm using amavisd-new-2.10.1 on fedora22 and occasionally receive "too
many open files" where it's necessary to just restart amavisd to get
it going again.

837D0346927     2973 Sun Dec 13 23:11:20  donotreply at nexusworldservices.com
(host 127.0.0.1[127.0.0.1] said: 451 4.5.0 Error in processing,
id=25071-05-40, check_init2 FAILED: Could not open /etc/resolv.conf:
Too many open files at /usr/sbin/amavisd line 17747. (in reply to end
of DATA command))

I've search around quite a bit, and the only suggestions I see are to
use ulimit to increase it. This won't survive a reboot, so I wondered
how to do it at the system level instead?

Will this even fix the problem? I notice now amavisd is using quite a
few more than the normal 1024 limit already:

# lsof |grep amavis|wc -l
1772

# ulimit -n
1024

Is this a PAM setting that I must change?

Any help greatly appreciated.
Thanks,
Alex