procmail/formail syntax question

[stan]

I'm trying to get procmail to rewrite the TO: header. I've tried something like:

TO=`formail -xTo:`

# is moved to "viruses".
:0:
* ^X-Virus-Status: Yes
| formail -I "To: is_virus, $TO"


# Mails with a score of 15 or higher are almost certainly spam (with 0.05%
# false positives according to rules/STATISTICS.txt). Let's put them in a
# different mbox. (This one is optional.)
:0:
* ^X-Spam-Level: \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*
| formail -I "To: certainly_spam, $TO"

# All mail tagged as spam (eg. with a score higher than the set threshold)
# is moved to "probably-spam".
:0:
* ^X-Spam-Status: Yes
| formail -I "To: probably_spam, $TO"

But this does not seem to be working.

What am I doing wrong?

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