Difference between sql agent account logged in as NTLM and UPN? Can someone please tell the difference between a sql agent account logged in as NTLM and UPN?

What is the difference if the sql agent account is logged in as:
domain\username and username@domain.com?

In what way will the functionality affect and where?
Would it affect 'execute as' statements in sql stored procedures?
Microsoft SQL Servers do not allow the use of User Principle Name (UPN) addresses for service accounts.  There is a post from a few years ago in Microsoft Connect and a more recent post:

https://connect.microsoft.com/SQLServer/feedback/details/519008/upn-user-principal-name-as-services-account-name#details

http://www.ryanjadams.com/2014/02/error-authenticating-proxy-sql-and-upns/#axzz2x0igTI3n

Therefore you need to stick with the DOMAIN\USERNAME format for the service accounts.

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