### 6.4.1 Information on VERP

You will note in the alias generating script for 2.1 above, there is a line for VERP that has been commented out. If you are interested in VERP there are two options. The first option is to allow Mailman to do the VERP formatting. To activate this, uncomment that line and add the following lines to your mm_cfg.py file:

        VERP_FORMAT = '%(bounces)s-+%(mailbox)s=%(host)s'
        VERP_REGEXP = r'^(?P<bounces>.*?)-\+(?P<mailbox>[^=]+)=(?P<host>[^@]+)@.*$'

The second option is a patch on SourceForge located at:

http://sourceforge.net/tracker/?func=detail&atid=300103&aid=645513&group_id=103

This patch currently needs more testing and might best be suitable for developers or people well familiar with qmail. Having said that, this patch is the more qmail-friendly approach resulting in large performance gains.