A few days ago I upgraded sendmail to 8.14.1-4.2 on a FC7 server which has been running faultlessly for months.
Ever since, for every MAIL FROM: and RCPT TO: it recieves as part of an incoming connection, it pauses for at least 45 seconds doing DNS lookups (I assume). As you can guess, this *really* slows down throughput.
It never took anything like that long before, and a DNS MX lookup of a host takes about 40ms, so what is it doing for 45 seconds?
I've checked everything I can think of - any ideas?