[OT] Anyone experience DoS symptoms with mta*.adelphia.net?

[dnsadmin 1bigthink.com]

Hello All,

I've got two different users under milter-greylist that are receiving 
mail from mta*.adelphia.net and it looks like a DoS, but could be a 
misbehaved MTA. The DNS does resolve to a host.

Jan 25 19:55:42 mxt milter-greylist: l0Q0jqpr027000: addr 
mta8.adelphia.net[68.168.78.196] from <> to <someone at here> delayed 
for 00:05:10 (ACL 634)
Jan 25 19:55:42 mxt sendmail[27000]: l0Q0jqpr027000: Milter: 
to=<someone at here>, reject=451 4.7.1 Greylisting in action, please 
come back later

ALSO:

Jan 26 20:33:58 mxt milter-greylist: l0R1XJAh017040: addr 
mta10.adelphia.net[68.168.78.202] from <someone at adelphia.net> to 
<someone at here> delayed for 00:14:21 (ACL 634)
Jan 26 20:33:58 mxt sendmail[17040]: l0R1XJAh017040: Milter: 
to=<someone at here>, reject=451 4.7.1 Greylisting in action, please 
come back later
Jan 26 20:33:59 mxt milter-greylist: l0R1XJAj017040: addr 
mta10.adelphia.net[68.168.78.202] from <someone at adelphia.net> to 
<someone at here> delayed for 00:14:20 (ACL 634)
Jan 26 20:33:59 mxt sendmail[17040]: l0R1XJAj017040: Milter: 
to=<someone at here>, reject=451 4.7.1 Greylisting in action, please 
come back later

I changed the names to 'someone' to protect the innocent.

Of course, I've reported the problem and their abuse at adelphia.net 
does not deliver.

Should they be whitelisted in milter-greylist?

Thanks,
Glenn Parsons