IP blacklisted!!

It looks like at some point a Smarty customer likely had some malware on their device which was attempting to send out spam emails while that IP address was assigned to them. What doesn't help is that Smarty, alongside most UK mobile networks, uses CG-NAT (carrier grade network address translation), meaning the same external IP address is shared by multiple users at the same time.

All you can do is toggle airplane mode or reboot your phone, which should result in you getting a different IP address assigned, hopefully one which isn't blacklisted.