Well, there are (at least) two rules to follow about "form-to-email".

First, do not fill in the to: or cc: fields (or any other field that can have a delivery address) from any form data. Hardwire it into the program: 

print SENDMAIL <<"END";
To: some.person\@my.domain.only
Subject: $FORM{subject}

$FORM{detail}
END

[download]

Second, if you use any form data in the header (like subject above), make very sure that the data cannot possibly contain newlines or anything resembling newlines. Otherwise, a bad guy can insert a newline into the data (not using your form, but using their own formstuffer), and insert a to/cc/bcc field, thus losing the protection provided in the previous point.

Does that help?

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

In reply to •Re: Re: •Security Alert (was Re: Re: checking for null variables) by merlyn
in thread checking for null variables by edahm

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