Did you actually hand the mailers to a postal worker, or did you put stamps on them, and throw them in a mail box?

If they went into the mail box, then they go the way of all letters, into the sorting machine. At that point, nobody reads what you wrote on the front and back (hand stamp)

If you gave the mailers to a postal worker, did you ask him to hand stamp them for you?
If not, then see the above serenio.

Regards,
Ralph