Well I've never been charged to mail letters/bills that already had postage on them!

But I have (at dif locations & across dif chains, so not unique to Marriott) been charged a fee for receiving/storing packages (even if small in size). It really varies, but I think is more common in convention locations. 99% of the time in my case it actually was for convention stuff, not personal.

One time I got a customs fee charged to my room at the AMS Marriott. Client didn't do paperwork properly & had marked CDs. Customs thought it was music instead of press kit CDs (ie, the latter having no 'value'). I was just grateful the hotel accepted package & paid customs rather than refusing (I didn't arrive until 2 days later), as it would have been a problem not to have the CDs during press mtgs.

Cheers.