eswish.net is the name of both my incoming and outgoing email services.

I have the following problem at a particular customer site, on just one
computer at that site.

An unknown error has occurred. Account:
'eswish.net', Server: 'eswish.net', Protocol: SMTP, Server Response: '550
not a local host yahoo.com, not a gateway', Port: 25, Secure (SSL): No,
Server Error: 550, Error Number: 0x800CCC69

I suspect it is a problem with that computer's Windows installation, because
none of the other computers at that client site have this issue and the same
problem exists for both Outlook and Outlook Express.

Anyone out there ever seen this one????

My server provider is www.HostMySite.com and they have told me they don't
know how to fix the problem. I have tried everything short of tossing a dead
cat across the road during a full moon and am about to try reinstalling
Windows XP or going back to a restore point, if possible. (Neither of these
options sound like much fun, so I'm hoping someone out there has seen
exactly this symptom and has a fix for it)

Sincerely,
Frank Rudolph