I had been using Outlook.com for my emails, with my emails being forwarded from my server. Several had not got through, so I turned off forwarding and went back to Live Mail. I could receive but not send - error 0x800CCC0E. Socket error 10060.
I deleted that account and remade it, checking my info against my husband's similar account. Still couldn't send as it insisted on sending from my old account although it had been deleted.
I deleted all accounts and remade my primary one. Still couldn't send - it was still using the old deleted account.
I removed Windows Essentials from my computer and downloaded a new copy.
It still won't send and uses the old deleted account. I can see an error in the old account - STMP instead of SMTP. The subsequent account doesn't have that error, but Mail won't use it.
I went to Add/Remove Programs and repaired Windows Essential - still no change.
The only thing I can think of now is that I only downloaded the MAIL program in Essentials.
Thanks for your help, Jane