[SLUG] Weird DNS prob

["zipworld mail" <slug@xxxxxxxxxxxx>]

Not sure if this is the forum but both sites do use linux!

I can't send email to a particular host I know well. They can't send me
email.

I can't ping or traceroute to them and visa versa, yet we're both able to
see and access the rest of the net.

Is this a weird routing issue?  The two sites are ADSL, one netspace one
pacific internet.

This was all working fine until two weeks ago. It's odd. No config changes I
can think of.


TIA


Stuart