My configuration matches yours, so I have no suggestions, unless the Plusnet comment relates. If so, how? Thank you.

Thanks for checking that. I wondered whether there was a password element to the problem. From what I can see there is only a password entry under the Outgoing Server setting (and its only a problem when sending messages). However, surely there should be a password check when downloading messages ? Having said all that, I have used the same password for accessing my Outlook webmail without any problems. I am sure there is no Plusnet influence as I have created a new different account on my PC while I try to get it working and not interfere with my existing shaky (Greenby/Plusnet) arrangement. Is there a way to involve Mozilla support do you know ? Thanks in advance, Bob

> Is there a way to involve Mozilla support do you know ?

You are already using it :)

Microsoft account sets all email addresses as 'alias'. eg: any @hotmail.com; @outlook.com or any email address using the outlook/office server. Microsoft requires all email addresses to use the same password as used to access Microsoft account.

How many email addresses have you got in the Microsoft account ? One of those email addresses will be set up as 'primary'. Whatever email address is set up as 'primary' will be the only email address that Microsoft will allow to be used as smtp in a third party email client.

Senario: Assume you have two email addresses eg: name@outlook.com and name@hotmail.com If name@outlook.com was set up as 'primary': In Thunderbird you can create the two accounts set as imap, but both accounts can only send using the name@outlook.com email address. That means you would have to set up the name@hotmail.com smtp to use name@outlook.com. AND to make sure any replies go to the correct address, in the hotmail account you would also set up the 'Reply to Address' as the name@hotmail.com.