I have an iPhone SE running iOS 14. If I connect to 4g then I can’t sent emails and get an smtp error. However sending emails is fine using Wi-fi and also if I connect to a vpn via 4g.
spamhaus is suggesting my public 4g address of 220.127.116.11 is listed in the PBL which states
Outbound Email Policy of Virgin Media for this IP range:
It is the policy of Virgin Media that unauthenticated email sent from this IP address should be sent out only via the designated outbound mail server allocated to Virgin Media customers. To find the hostname of the correct mail server to use, customers should consult the original signup documentation or contact Virgin Media Technical Support.
so given that I am using port 587 to connect to Bt and authentication then why am I being blocked ?