I raised a ticket via Twitter with BT Care.
Received a call this afternoon to say theycould find nothing wrong with my account. Advisor said needed to follow next step to see if problem is fixed before moving to next level of support. Standard help desk response.
Received two emails. One contained this link
One mentioned settings
I've changed my settings to use SSL - although I don't think it will make that much difference.
It hasn't played up tonight (before or after) I have changed the settings. Doesn't mean it is fixed - only the random/ad-hoc problem has not occcured.
Changing to SSL won't help with the current problem, but is advisable anyway as it gives a secure connection.
There is still a problem.
Some diagnostic information in case it helps. I use Outlook to collect mail. My BT email accounts are still with Yahoo and are all showing the problem. If I get a fail I (manually) tell Outlook to try again and it usually succeeds after one or two tries. There is no problem with other email accounts with Yahoo.
Wild guess: the problem lies in the system being used to decide whether the BT account is still with Yahoo?
Have been able to send email reasonably reliably now for 3 days (fingers still crossed), and have noticed that level of spam has significantly reduced from before 3 Dec when email sending problems started, which (together with regular newsfeed emails, and emails from IoD and BT ending up in spam folder around time of the email sending problem) backs up my theory that BT has been changing their spam filters to reduce their poor spam performance, but with knock on impact on email performance ...
BT Digital Care called me just now following my formal complaint 4 days ago - wanted to tell me that they couldn't help if it was an issue with BB or MacMail, they only support webmail! But if I want to pay for an expert to help with my BB or MacMail I can do so. I explained the background of no changes on my part, suspicious spam filter activity, 100's of people with same issue on fora, lack of communication from BT .....
To the Moderator (as I told BT Digital Care): 2 simple requests
a) when BT is undertaking work on the system PLEASE COMMUNICATE, honestly, regularly and clearly. Especially when your user community makes it clear in both quantity and similarity of feedback that there is an issue.
b) please ask your management to pay more attention to the service provided by for BT Mail customers: if the unreliability of the BT Mail service starts to exceed the hassle of changing my email addresses, I will have a big incentive to leave BT. BT is a reputable major company - it should respect its customers.
For those who seem to be caught in the BT Yahoo/BT Mail migration situation, please don't lose heart - I have migrated, and once I had my settings sorted out with BB (via my mobile provider) and on MacMail (me, new settings), it has worked ok - not great, and so far 2 periods where cannot send email reliably for days (in April and over the last week). Keep pushing BT.
E-Mail performance using an Outlook client has improved markedly today compared with that of recent days.
I suspect that Pleshey02 is right in identifying the cuplrit as changes to the spam filters. I doubt however that any changes will have been made as part of attempts to improve the perceived poor performance in the handling of spam per se, but rather because of the heightened threat level. I have no inside knowledge but I'm virtually certain that the same servers and/or applications that perform spam filtering are also used lawfully to flag any e-mails deemed to merit the attention of the security services.
I very much doubt it has anything to do with spam filtering. The problem has been rejected logins so not even getting as far as connecting to the server. 2 mail systems managed by 2 discrete companies trying to operate from one user credential database is always going to be a recipe for disaster