E-mail provider is Outlook 365.
When you change domains the mailbox MX records can sometimes take a few days to update at the new host address.
However if it’s been a few days, you might then need to possibly change your outgoing mail settings in eM Client to match the new server.
Have you been advised by Outlook 365 support staff of any SMTP server address changes ?
It’s not DNS or SMTP server issues. It’s to due with this stupid Oauth authentication system Microsoft rammed down our throats a few years ago. It opens a page on the web browsers and then asks you if you’re signing in with emClient. Sometimes it looks like it works, sometimes you get an error message that looks like this:
I can download e-mail fine. I just can’t send it because it won’t authenticate properly.
It’s not DNS or SMTP server issues. It’s to due with this stupid Oauth authentication system Microsoft
Ok. Have you tried removing and readding the account via the automatic account wizard ?
Also have to tried setting a different browser as the default browser when it’s authenticating the OAuth token ?
As could possibly a problem with the account in eM Client, or could be the OAuth authentication problem might be related to the browser type.
Also try closing eM Client, and then go online into your Outlook 365 account and try removing the eM Client OAuth token, and then try opening eM Client again and see if it authenticates ok.
Apart from that sometimes eg: Optionally installed background resident programs can cause interference with browsers authenticating like eg: Firewall / Security programs or VPN’s etc. So if you have anything like that optionally installed other than what comes default with your OS, then try completely disable those to test.
There were probably two things going on. One was that the account name e-mail and my default e-mail were different and I think OAuth didn’t like that. I switched that on the Office 365 end.
The other thing, which probably meant it had been working a few times when I didn’t realize it was that clicking on Send and Receive All in emClient doesn’t try to resend what’s in the Outbox. I had to open the message and click on Send from there in order to get it to retry. And it ultimately went out.
So I think it’s fine now.