We are having this issue to since we upgraded to Wave 15 on 1st Dec. Fortunately we had a listserv upgrade in the works so am hoping that fixes it too.

Our install of OWA, seems to put in the from line in a reply like this:
From: listinfo [[log in to unmask]] on behalf of Daniel Nisbet 

Whereas the upgraded Wave 15 of Office365 looks like this:
From: listinfo <[log in to unmask]> on behalf of Daniel Nisbet <[log in to unmask]>

Which listserv rejects.

Regards,

Daniel