Starting a few days ago, a few of my users have reported that they have
been unable to receive email at my mail1 server from certain domains.
My uptime was about 180 days and do not recall making any recent
changes to my config (sendmail or DNS)

A check of the problem showed that when I telnet to mail1 from mail2
(at another location)
telnet mail1.domain.com 25
it consistently takes 65 seconds to get the greeting:
220 ns1.galacticnet.com ESMTP Sendmail 8.13.6/8.13.6
telnet to port 23 is instantaneous and mail1 consistently has over 90%
idle time

If I telnet to the mail1 server from the mail1 server:
telnet localhost 25
the response is instantaneous!
I had my ISP telnet to mail1 from only 1 hop away, and the get the same
65 second delay!

I had not been using GreetPause but today have added it to mail1 server
mail1.mc now has:
FEATURE(`greet_pause',`500')dnl
and
mail1 access now has
GreetPause:_ip_of_mail2 100
GreetPause:_ip_of_mail1 15000
However, there is no change in the times to get the greetings
Still 65 seconds from mail2 to mail1 and still instantaneous from mail1
to mail1

Any ideas where the delay has come from or how to get rid of it.

I am getting some mail at mail1 and some mail goes to my secondary
mail2 server, but users are reporting that some is getting bounced.