Due to Vodafone ending email services, my friends set up a gmail account to forward their clearnet emails to. I tested it for them by sending them an email to their old clearnet address and get this message:
554 5.7.1 DNS Blacklisted by safe.dnsbl.sorbs.net
Anyone got any ideas to help?
Vodafones only suggestion was to turn off their modem for 15 minutes then turn it back on but this didn't help.