Tal,
I'm not Sage of course, but I'm horning in on your question anyway.
I think it is ABSOLUTELY alright for you to ask H to remove XOW from his e-mail address book...in fact, I think you've every right to ask that he also add a block from it.
There are "things" that I am going to request/demand of my H. I know that while with OW #1 that he got into a different kind of music (saw them in his car way back then and when I asked about them he blew them off...dumb me) so I will ask that he bring NOTHING and I mean absolutely NOTHING to OUR home that is even remotely connected to the two OWs...music CDs, cologones or anything else THEY may have given him. I know I can't erase his memories, but I don't want HIM to have ANY tangible or casual reminders of his time with THEM, especially NOT IN MY LIFE OR HOME.
T2