ignored user can't write to me

Ignore user only deals with hiding content created by a user.

Privatemsg already has an option to allow you block another user
from sending you private messages. If the privatemsg module
has an API hook that this module could use to also block a user
from sending private messages then perhaps this could be done.

Just bumping this issue - privatemsg HEAD does allow other modules to block users, which the included pm_block_user leverages.

The two hooks that need to be linked into are:

1. hook_privatemsg_block_message($author, $recipient) - to block, reply with a message giving a reason.
2. hook_privatemsg_pm_controls($pmid) - use this to add per message links to allow/disallow future messages from the author.

further, if needed, the query builder can be hooked into to "hide" messages from specific authors.

When privatemsg makes an official release with this API function in there then I'll take another look. I don't want to add in features that rely upon something in another module that has yet to make it out of HEAD.