This is good! I have searched for this actually.
However this seems to lack the most important thing (for me): the global usage percentage of a particular feature, which is the #1 deciding factor whether to use a HTML/CSS feature or not.
However this seems to lack the most important thing (for me): the global usage percentage of a particular feature, which is the #1 deciding factor whether to use a HTML/CSS feature or not.
The only people who can really use the headers to identify which email clients are in use are people who maintain very large ISPs. Although, even then, keeping track of the results of the IMAP ID command are probably more useful.