If you are sending mail with a script, and have something like print(MAIL "To: someone\@somewhere.someorg\n"); the @ needs to be escaped. Of course, one could use single quotes here (except for the newline), but one might want to store the address in a variable and have that and some other things interpolated, and then the @ may cause problems if it's not escaped. It is often possible to get around that with some cleverness, but sometimes it's easier to just escape the troublesome characters.
(At least, that's what I imagine the OP might be dealing with.)
(Update: After thinking about it for a while, I can't really think of a convincing reason to escape the @. My brain is just not working well today...please ignore me! I'll shut up for the rest of the day.)

In reply to Re^2: Having a problem replacing "@" with "\@" by chas
in thread Having a problem replacing "@" with "\@" by TASdvlper

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