Blacklisting receivers is definitely a thing MG engages in, but I'm wondering if anyone knows anything about senders.
I've only used MG for donations, usually to flagged countries and to several blacklisted receivers. The past several times I've tried to use their services, it has resulted in more than the usual 'my donation is on hold' NBD response. The last time (because I'm not dumping cash like that again) they had me re-confirm it after two separate phone calls, give a new number to my receiver, then marked it immediately as received while I was still on the phone. The receiver said he was told there was no such number when he went later, but there was a new person there. I'm afraid they're using my donations as a way to identify others.
I stopped using them completely and switched to places that could take card, but now that my site is having issues, I'm back to wondering if this is something anyone else has dealt with and how they got around it.