Converting email which has 2 or more newlines before it

There is a problem with converting plaintext email into the link when there are 2 or more newlines before the email. E.g.

<!-- 2 newlines before email -->

test@example.com

will be converted in _bbcode_filter_process function into

<p>test@example.com</p>

and after that conversion into the link will fail b/c the regular expression which converts emails into links expects emails to start with tabulation, new line or empty space (see line 256).

I've implemented a workaround for this (see patch) but I feel that this solution should be more generic, like processing the links at the beginning of the filter process but I don't know how this can be done correctly.