This file is indexed.

/var/list/.etc/confirm-help.txt is in smartlist 3.15-22.

This file is owned by list:list, with mode 0o644.

The actual contents of the file can be viewed below.

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Your confirmation request was unsuccessful.  Please double-check the
following and try again:

1.  Did you include the word "CONFIRM" and the confirmation number in
the SUBJECT of your email?

2.  Did you copy the confirmation number exactly as written in the
confirmation email you received?

3.  Did you already successfully confirm your subscription?

It is also possible that too long a time has transpired between your
(un)subscription request and confirmation or that some list data was lost.
If you followed the above instructions exactly and still get this
message, please send another (un)subscribe request and get a new
confirmation number.