What is the difference between date and MailDate in imap email headers?

Question

PHP

The manual on php.net decided not to say anything about the top-secret MailDate header.
Google didn't come up with anything either. Like the RFC on IMAP.

Answer 1

Date - the date of the letter from the header Date: , which is put on the side of the sender
MailDate - most likely the date of creation (receipt) of the letter. Those. if you copy an old letter to the server, then it will have an old Date and a fresh MailDate.