I'm just reporting for Community's benefit of anyone viewing this topic in isolation that you've indicated the issue is resolved. You've got two topics running on the same issue. If you don't want me to cross-link I can merge into one topic then we don't have to duplicate everything and it'll save me a whole lot of work.
I can't tell why the issue is resolved because I don't know what sending address one.network are using, what sending IP address one.network are using. I've flagged up in the TalkTalk workflow that one.network have three mail services listed as designated senders. Perhaps one.network have switched senders because of blacklisting of a sender's IP address? I couldn't see any obvious issue with any of their senders though. Perhaps one.network were using an IP address not listed as a designated sender. Perhaps one.network have reset a suppression on sending mail to your email address.
Now that you're receiving mail once more, if you wish to PM me the email header (View Source in TalkTalk Mail) then I'll be able to see if there's any potential issue. Redact your own email address for personal privacy.
Ady did say that a search of sender had been done and that had come up with a blank indicating no mail incoming. A search of your mailbox address was going to be made.
