We have protection in place to detect automatic responses and not forward them on. However not all automatic responses are labelled correctly and so some get through.
If you find automatic responses are getting continually being forwarded to your group there are a few things you can do.
Firstly if you have “Echo sent message to sender” enabled switch this off which will at least stop the automatic responder responding to their own message.
Secondly, if the automatic responder is not an administrator of your list you could try temporarily changing the “Who can send to the group” option to “Administrators only”, this will prevent them from sending to the group.
Finally, as a last resort, you could remove the auto responding member from the group, this will certainly make them stop!