If you are sending e-mail to me from a @yahoo.com address or from a service provider that uses Yahoo! as its wholesale provider such as BT Retail Broadband customers (@btinternet.com), you are unlikely to be able to send to me any more.  Why is this?  Because Yahoo! have decided to block my very recently allocated IPv4 address range so that I cannot send mail to any Yahoo! customer or any of their wholesale customers – presumably because they think I’m a notorious Russian spammer or something (since the /16 that this block of addresses is in seems to contain blocks of IPs from places such as Russia and Kazakhstan).  Which might be tempting to think, apart from the fact that my IPv4 addresses were blocked before I could even send them a single mail.  Despite having proper SPF records and DKIM signing all outgoing mail, attempting to send mail to their servers results in a message thus:

421 4.7.1 [TS03] All messages from 178.238.157.69 will be permanently deferred; Retrying will NOT succeed. See http://postmaster.yahoo.com/errors/421-ts03.html

Yahoo will not explain why my IPv4 addresses are blocked, they sent a canned reply stating that they will do nothing about it, and that their spam blocking methods are so secret that they can’t (read: won’t) tell me why, with apparently no right of appeal.  For obvious reasons, I consider this to be totally unacceptable behaviour on their part.

As far as I can tell, Yahoo! are the only major ISP who are blocking my address range, so using Hotmail, Gmail, etc. should work.

So, Yahoo, if you’re reading this – if you do not unblock my IPv4 address range on your servers (178.238.157.64/26), then your customers will not be able to send e-mail to me until you unblock them.

If you are a customer of an ISP directly affected by this, you may wish to take this matter up with them if you wish to carry on receiving e-mails from me.