(Exim 4.24) No host name found for IP address

[RedIndigo]

I see "no host name found for IP address" messages in exim logfiles a few thousand times each day. Some of our normal users have difficulties with this check. Is it a common convention that a sending MTA must have a dns-entry? Would it be possible (and wise) to switch off this check?

[Mr.Macroney]

I leave it on and if a problem arises, I white list the site temporarily while they get it fixed.

In the past, it used to be a lost cause for some places trying to get them to fix it but lately, it seems that when I identify the problem and send it to the proper people, they fix it fast... that is if they are supposed to be using that IP for mail services..

I suspect that is because a lot of places are now checking for that and won't budge when they find a site without it.