In reply to a post by XRaySpeX:

Problem solved!

In reply to a post by BatBoy:

It's easy to confirm: telnet mail.btconnect.com 587

You confused the wrong server with that port.

It's 'telnet smtp.outlook.com 587' that connects OK. All to do with Microsoft Office 365.

As I said

In reply to a post by BatBoy:

It seems that BT Business are migrating the email over to Office 365 and the new mail server is smtp.outlook.com.

The fact remains that he doesn't seem to have a port 25 issue witht the "home" ISPs, (I agree that that is surprising), and specifically said he wishes to use the BT SMTP servers both at work and "home"

Now I would like to hear from anyone who has a laptop where their email client, say MS Oulook uses their own domain name, and is able to use BTs SMTP servers both in the office and elsewhere ....

Which your solution does not achieve, but your idea when modified as I did does. Until he hits a port 25 block.

In reply to a post by BatBoy:

Having 2 accounts is changing settings

Not really, given all he wishes to do is avoid the users having to modify parameters. Selecting the account to send from hardly falls into the technical or complex category. If they select the wrong one it will simply fail to send and they then select the other.

So, you write an email and try to send it from the wrong account - what happens?
Does it say "send failed"?

In reply to a post by RobertoS:

The fact remains that he doesn't seem to have a port 25 issue with the "home" ISPs, (I agree that that is surprising)

True, but I'm trying to provide a general future-proofed solution, that will cater for a homeworker joining the office whose home ISP is O2 or Orange et al.

but your idea when modified as I did does.

What is your mod to my idea? I don;t see it!

Or do you just mean have 1 a/c with authenticated BT SMTP for Home and other with UNauthenticated BT SMTP for Office? In that case it does not meet my criterion of future-proofing .

In reply to a post by XRaySpeX:

Or do you just mean have 1 a/c with authenticated BT SMTP for Home and other with UNauthenticated BT SMTP for Office? In that case it does not meet my criterion of future-proofing .

Is this the first time you mentioned future-proofing?

It's implicit in my aim to cater for port 25 blocking ISPs as stated when I first propounded my solution, for those who understand logic.

Are there any more criteria you haven't mentioned?

Only the obvious one that it should work in all situations.

It's just that I think it's important to consider the OP's criteria rather than your own.