open outlook.
go to tools/account settings/ and double click on account
make sure incoming and outgoing server settings are correct .
click on 'more settings'/outgoing server
make sure 'my outgoing mail server (smtp) requires authentication' is ticked.
you may need to click on 'log on using' and enter your account and password and tick remember password, but normally the default setting of 'use same settings as my incoming mail server works fine'
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