The phrase "mailing date" refers to the date when something is sent or posted through the mail. It indicates the day it is put into the mail system to be delivered to its recipient.
Sentences with «mailing date»
Send mail Dating French women and single girls online. (myintimcity.com)
Marking emails as Spam Does it junk mail dating sites it from reappearing? (petesgrillandpizza.com)