Undeliverable replies (550 Auth)

[KatyK]

If I try to reply to a message, it almost always comes back to me as
undeliverable:

550 Authentication required. Help at
http://www.earthlink.net/go/emailsettings (failed to find host name from IP
address) This does not help.

If I reply from my webmail or if I write a NEW message from Outlook to the
same address, it goes without a problem. I have been using copy and paste to
put the message on a new email, which is a major pain! This does not happen
with every message or every time with the same addresses. Any ideas?

 

[Brian Tillman]

If I try to reply to a message, it almost always comes back to me as
undeliverable:

550 Authentication required. Help at
http://www.earthlink.net/go/emailsettings (failed to find host name
from IP address) This does not help.

The message indicates you are not properly authenticating to your outging
server. The web page shown in the error does explain how to do that. In
particular, read
<http://kb.earthlink.net/case.asp?s=st=45,e=0000000001731557712,k=7103,sxi=5&article=22873>