To answer VLT - one of the hosts I am using is also 1&1, so there may be a link there. However I have also had the issue from another account hosted by Webfusion. I too spent 2 hours on phone to 1&1, who tried lots of things and tested various servers. They eventually came back and said they were sure it was a BT issue.
BT spent less than 15 mins on the phone, before giving up and blaming the senders, when I tried to get them to look at it!
It is still happening intermittently.
As Pleshey02 says, all BT wanted to do was change passwords on one of the recieving accounts - they didn't seem to realise that if 20 different accounts all failled to receive at the same time changing the password on just one of them would NOT solve the problem.
To add to this string, the emails from my wife which bounced were from a 1&1 hosted email address, so it looks like it could be a problem between 1&1 and BT?
It might well be two issues here. When I look back at the problem I had from webfusion, which only occured once on one email, it has slightly different error message. So I may have been mistaken in assuming it was the same problem.
It is beginning to look like it is worth investigating the 1&1 to BT relationship issue more thoughly. Possibly both have a part to play in resolving this.
Well its certainly not a general problem, I have no trouble sending between my domain on 1 & 1 and btinternet.com
Good! 1&1 have jsut emailed me telling me to alter my SPF record!
Not got time to try until alter and I hope their instructions tell me what I need to add!!
I have added
v=spf1 ip4:18.104.22.168/24 include:_spf.mail.yahoo.com include:_spf.perfora.net include:_spf.kundenserver.de ~all
I've had this problem and I suspect it's BT bulk email filters between 1&1 and BT. It is intermittent but I've checked it by sending my emails, via 1&1, to a Hotmail address and a BT address. When they're bounced by BT they get to Hotmail!
It's VERY annoying, particularly for those trying to contact me. if they resend, more often than not, it isn't bounced. In the past when I've complained BT claims not to use bulk email filters. I don't believe them; but I suspect that's what customer facing people are told to say. Interestingly it's more likely to bounce if the sender is on btinternet!
I use 1&1 as my ISP and have two email addresses with them. One email address is for personal email and the other is for when I am the editor of our island's monthly newsletter (www.stronsaylimpet.co.uk) and send out very brief news updates about once a week to 150 subscribers. All was well until a couple of months ago when email to a random selection of btinternet.com email addresses started getting bounced back. Today I phoned 1&1 who told me to contact BT. I emailed email@example.com from both of my 1&1 email addresses reporting the problem. The email from my editor's email address was bounced back! I resent it and so far it seems to have been delivered.