valid sender domain

[beb]

Had an e-mail returned with the following message: "550 [PERMFAIL]
comcast.net requires valid sender domain"

What do I have to do to allow the recepient to get my e-mails?

 

[Roady [MVP]]

Hard to say with this little amount of information. Most likely you'll need
to enable authentication for your SMTP server.
See http://www.msoutlook.info/question/36