I believe many of the members here are aware of the spam signups issue.
I have found these domains so far.
tmomail.net
txt.att.net
txt.bell.ca
email.uscc.net
Perhaps we can have a consolidated list some place that could make it easier to keep track of these spam domains?
This list is pretty comprehensive. Using it on Magic Pages and I do not see any spam activity anymore:
Thanks @jannis
My lazy ass finds it tedious to remove " and , from that list 
You do know it was more effort to type the post here rather than removing a few " 
It could be a cool idea to put some automation in place to automatically notify you when 5+ email adresses sign up from a domain so that you can review and potentially block the domain if it’s spam.
Just had one of those funny looking emails come through via an opayq.com email address. Anybody else? I’m unsure if this email address is fake or actually real, and whether opayq.com should be added to the list of blocked domains.
Got a few spam singups from edny.net today
yep, got one too, well there goes my joy for a new member signup! 
@Abhishek_Prakash Please add the following domains to the list. It might help others.
vtext.com
msg.telus.com
mymetropcs.com
pcs.rogers.com
email.uscc.net
txt.bellmobility.ca
fido.ca
It seems that I cannot edit my first post unfortunately 