Which should I use the md5 challenge response vs ntlm vs http md5 digest?

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which to use md5 challenge response vs ntlm vs http md5 digest

In selecting alternative outgoing mail server I submit user name, password, and ssl. For authentication it requests 1 of the following 4.
Password
md5 challenge response
ntlm
http md5 digest

Which should I use and why?
Please advise.
Thank you.