Summary

This post is about GNU Mailman and shows how to update the post id which appers in subject_prefix as prefix number.
It might be useful if you migrated Mailman servers using subject_prefix option.

* "Mailman" in this post means not Mailman3 but Mailman2, because I use OpenBSD.

Tutorial

Use withlist, "the most powerful and flexible script in Mailman", to manage the database.

# /usr/local/lib/mailman/bin/withlist $LIST_NAME
Loading list $LIST_NAME (unlocked)
The variable `m` is the $LIST_NAME MailList instance

Lock the database files and update the post id.

>>> # check it
>>> m.post_id
current number

>>> # update
>>> m.Lock()
>>> m.post_id = 9999
>>> m.Save()

>>> # validate it
>>> m.post_id
updated number

Quit the prompt.

>>> quit()
Unlocking (but not saving) list: $LIST_NAME
Finalizing

Done :)