First I need to know What operating system you use and what is the error message displayed.
What kind of mail client are you using? If SPA is checked, make sure it actually needs to be checked. Is it POP3, IMAP, Exchange?
I am suspecting that your email server may have "Log on using Secure Password Authentication (SPA)" enabled.
If so, then you might just have to click on the feature, and maybe perhaps set whatever authentication is needed (usually it is the same as your name and password).
Also you can refer to the KB link :
You cannot connect to an MSN POP3 server from Outlook 2007 or from earlier versions of Outlook on a Windows Vista-based computer
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