Help On Auxiliary Markings

I need help identifying two auxiliary markings on this 1886 cover: (1) the purple circular "Phila. PA/May 16/Advertised" mark on the front and (2) the black circular "Phila. Post Office/June 18" mark on the back.

I've seen "Advertising" marks on other covers from this era, but I have been unable to find a clear definition or meaning of their use. If anyone knows and/or can point me to a resource, I would much appreciate it.

As for the extra Philadelphia mark on the back, I wonder if that is from the Dead Letter Office in Philly. The "Letter returned to the office by Carrier" is one clue to that possibility. That label does not appear in Scotts, but a nice write-up can be found in "Post Office Seals of the United States and Possessions" by Jim Kotanchik.

Thanks!

Struck when the Philadelphia Po couldn't find the addressee, so it was advertised in the local paper.




Think this was when Philadelphia gave up, sent it to dead letter office.

Note the pencil marking "Removed" at the top. An article in the Aux Markings Club newsletter (page 9) shows various handstamps for "removed", "removed - present address unknown", "removed - left no address", "moved, left no address", etc.
https://www.postal-markings.org/amc...-issue71.pdf

Adding to the timeline that littleriverphil suggested:
May 13 - letter arrived in Philadelphia,
Possibly carrier took it out for delivery or perhaps the central PO already knew the addressee had left the address
May 18 Post Office places a notice in the local paper (advertises) "Hey, we have a letter for Mrs. Grove, does anyone know where she went?"
June 18 No response within 30 days, return to sender. Oops, there is no return address, send to Dead Letter Office.

Edit: adding images of similar 'Phila. Post Office" markings but with "DEAD" at the top, from 1865 and 1870s. Not sure if yours from 1886 is a modified marking to remove the word DEAD. Maybe customers thought this meant the addressee was dead, not that the letter came from the Dead Letter Office. Just hypothesizing.

First is 1865 from a Rumsey sale (83-42), the second from a current Phil Bansner offering.

Thank you both. This is very helpful.

Regards.

If anyone out there has access to the leading Philadelphia newspapers from this period it would be interesting if he could find the advertisment and show an image of it. This normally was published as a list once a week. But I think that in some cities it was only published as a list they put up on the wall in the public part of the Post Office.

I actually did check the Philadelphia newspapers from May and June 1886 on newspapers.com. I tried several search terms and got zero hits. I'm undeterred, however, and will continue to poke around.

By the way, Richard Frajola's website has a paper that shows a few examples of "advertised" covers with one-cent postage due stamps. This is the link: https://www.rfrajola.com/Dues/Dues.pdf. This particular cover was never picked up, so no postage due.

I LOVE the label on the back!!!

An even earlier, 1850s Philadelphia DEAD.