X-Mailer header mapping to actual version of mail.app used to send message When email is sent using Mail.app a Apple Mail (x.xxx.x) X-Mailer header is added to the message. Is there a way to determine which actual version of the app was used to send the messages?  In Lion Version 5 the header is (2.1244.3).

Is there some sort of formula that determines what the numbers in the header are?  Is there any way to determine the version mappings from older versions?
Simple answer - no, there is no easy way to tell from just the number.

However, I did a Google Image search for screenshots of the "About Mail" window, and found the following correlations between Mail version numbers.


Mail 5.2 = 1257
Mail 5.0 = 1244
Mail 4.3 = 1081
Mail 4.0 = 1075
Mail 3.6 = 936
Mail 3.5 = 930
Mail 3.4 = 928
Mail 2.1 = 752


If you're wanting to match to versions of the OS:


Lion: 12xx
Snow Leopard: 10xx
Leopard: 9xx
Tiger: 7xx


"About Mail" images found on these (and other) pages:


http://www.ecu.edu/cs-itcs/mac/Apple-Mail-Settings.cfm
http://gseis.ucla.edu/administrative-support-units/educational-technology-unit/etu-documentation/email-apple-mail