The majority of the time, i= will be precisely an email address,
I've been collecting the DKIM signatures on my incoming mail, and
I'm surprised how few of them have i= at all. Ignoring my own
signatures, I see some from Cisco where the i= typically matches
the From address, a couple of spams where the i= matches the d=,
e.g. d=foo.com i=(_at_)foo(_dot_)com, and that's it.
By far the largest stream of DKIM signed mail is from gmail which
doesn't use i=.
R's,
John
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