Problems with verifying email address and SMTP set...

Question

I have recently moved over to BT Infinity Broadband and regularly work from home.  Recently I have been unable to send work emails (provided by 123 Reg) and having searched the forums I found a solution by using ny btinternet login details and verifying my email address.
However I have been able to verify two of my work email addresses but not the main and most important one.  Each time I try I get an "invalid email address" error message.  This is not causing too many problems with Outlook 2010 as I can still send and receive emails at present, hopefully this will remain.
However I do also use a case management software which sends emails.  It requires a SMTP server details and port number.  I have replicated these with the ones from Outlook, mail.btinternet.com and port number 465 but I am unable to send any emails.
I would be grateful if anybody could help me to verify my email address and also suggest what settings I would need for my case management software.
Many Thanks,
Will

Answer 1

I am a BT Premium Mail customer for my BT Talk21 e-mail account.
All was working fine on my PC and on my Mobile when I left the UK on 18t Sept.
In Greece, I was accessing e-mails, and responding to them, via the COSMOTE mobile network.
The problem started around 1st October, when I found that I could not reply to e-mails via my phone ("Sending Failed") - it would sometimes work if I switched my phone off an back on again, but I just couldn't send e-mails from my Android phone.
On my return to the UK, on 3rd Oct,  I found that I couldn't send e-mails via my Outlook 2010 client on my Windows 7 Computer, directly connected to my router-  getting error message 522 (account set up as POP3)
Test message returns:
"Send test e-mail message: Your outgoing (SMTP) e-mail server has reported an internal error. If you continue to receive this message, contact your server administrator or Internet service provider (ISP).  The server responded: 522 Your message has not been sent as you are accessin"
So, 2 separate devices, connected differently, where experiencing the same problem - the commonality BT E-mail severs.
I spent 2 days of absolute hell with BT's Indian call centres who were worse than useless - refusing to accept that this was a BT sever-related issue.
VOL 012-*********** – 4th Oct
VOL 012-*********** – 4th Oct
On my Mobile, as a test, I deleted my (POP3) mobile account on my phone, the idea to re-instate it.
On trying to set it up again, the BT mails servers wouldn't allow me to set it up as POP3 (even though up until the point of the problem it was POP3).
However, it eventually allowed me to set it up as SMTP/IMAP - and I can now send and recieve e-mails on my Talk21 account on my mobile. Although, being IMAP/SMTP it now deletes mails off the server if I delete them on my phone - which I found out the hard way.
My Outlook client on my computer still cannot send e-mails - returning the error code 522.
I have also accessed my account via webmail (which seems to work both ways) and have changed and verified my passwords, but the problem still exists.
In addition, my daughter also has a Talk21 Premium Mail account, and accessing via a different computer Microsoft Mail on a Vista machine, and she is experiencing the same problem.
I find out today that BT is withdrawing from Yahoo and is changing/has changed it's e-mail systems.
The problems I and my daughter are experiencing appear to be general BT Mail Server problems that need to addressed centrally, and not a single-user level as the likelihood is that many are affected.
I would like BT to look into this as a matter of urgency.