[Mailman-Users] Increasing volume of distributed subscription attacks (was Blocking or holding subscribe requests when email address contains "+")

[Robert Sparks]

David Gibbs wrote:
 > I've been getting a lot of subscribe requests from bogus email 
addresses that look like: adfslij+32987234 at gmail.com.

You're not alone. The subscriptions have also moved on to include 
addresses at SMS gateways after we added filters similar to what the 
thread suggested.

In case others are also dealing with this at volume, some background on 
what the IETF mailman admin is doing:

https://mailarchive.ietf.org/arch/msg/tools-development/p4iI5kxO-J1LZR5CQLerZYflHc0
and
https://mailarchive.ietf.org/arch/msg/tools-development/P9mDSeRrvgUAD_tFzYqgDbOkUpM

If anyone has a mitigation strategy that's working well, please let me know.

RjS