Originally Posted by jalbrizio
12/31/1969 is the Birth of UNIX thus 12/31/1969 = 0. its caused when your email app cant read your system date at the time it gets the email.
That's close, but not it.
1 January, 1970 at midnight is the beginning of the UNIX epoch. It's an arbitrary date and time that's pretty close to when AT&T UNIX was developed.
If you see a date of 31 December, 1969 that's an indication that either the time and date are unknown, corrupted, filled with nulls, or otherwise illegal to the UNIX operating system and its work-alikes.
When it comes to e-mail, a 1969 date is a pretty reliable indicator that it's spam.