Problem sending to a specific email

[daph]

Hi,

I was sending an email via sendmail to 10 recipients...all of them received the email except for one. Here are the errors for that failure:

----- Transcript of session follows -----
554 rewrite: map @ not found
... while talking to something.pch.gc.ca.:
>>> MAIL From:<something@domain.com> SIZE=353
<<< 553 5.1.8 <something@domain.com>... Domain of sender address something@domain.com does not exist
501 recipient.email@pc.gc.ca... Data format error

Where something@domain.com is the box where sendmail is sending from.

I don't know if this is enough information to get some help from you guys or not. I'm just really new to sendmail and I would really appreciate if anyone could give me an idea on where to start looking to fix this error.

Thanks a bunch,

Daph