I sent out a book and DC shows it was delivered. It hasn't been marked received and the requestor has their account on hold. Can I still PM them to see if they actually got the book? Can they mark it with their account on hold?

I posted a similar question earlier today and was reassured that the shelf being on hold doesnt actually mean the requestor is not home. It could simply be that they dont have enough money to pay for postage or just want to take a break from sending books. Whatever the reason, you should still be able to PM them and check up on the book.

Is the book about to go lost? If not, I wouldn't bother to PM them just yet. DC scans can be less than accurate.

I wouldn't PM unless the book is really close to going lost.  If you used PBS DC then you have your credit.  The fact that they took the time to put their account on hold is a good sign.  That means they are just on vacation or too busy or poor to mail books out right now. They can still get PMs, use the message boards, order books and mark books received. 

It won't go lost for awhile yet. I'll wait a week or so before I pm them. Thanks for the help.

Keep in mind that in many areas of the country it is time for spring break in schools, and many are out for a week. It's quite possible the person may be traveling this week (or in upcoming weeks).

PBS DC will give you your credit when it's scanned by the USPS, so if you're needing credits, this may be the option to use when you're needing credits. PBS postage will give you instant credit when you mark it mailed.