Comment 6 for bug 266158

Your site has really big amount of bounces get. I'd suggest
try one or two of these:

1. Set bounce_processing to "No" in admin->bounce page.
2. Set REGISTER_BOUNCES_EVERY = minutes(1) in mm_cfg.py
and process bounces before they accumulate to Giga-Byte.
3. Rewrite your MTA's alias file as
    your-list-bounce: <email address hidden>
 and process the counce manually.
4. Rewrite your MTA's alias file as
    your-list-bounce: /dev/null
 and forget about the bounces totally.