Why was my letter sent back to me as "returned to sender" when all my other mail has gone thru?

There are SEVERAL possible reasons. The first two that come to mind are:

1. The post office made an error.

2. Someone at the jail made an error.

Note: If the POST OFFICE DOES NOT stamp items 'return to sender'. They use a yellow sticker that would have included SOME explanation of WHY. It sounds like it WAS delivered to SOMEONE, and THEY stamped it 'Return to Sender'.

It was probably a simple mistake on behalf of one of the postal workers, they are human and it may have just been a really hectic day and they made a mistake, or you may have made a very small error on the addressing such as incorrect postcode or something similar.

I wouldnt worry too much at this point if you keep having further mail returned then contact your post office and inquire as to why it is being returned, and they will answer your query.

The other option of course is that your gf has decided not to accept your mail, if that is the case you will need to take it up with her.

It could be as simple as someone making the mistake to sort that letter into a box for "Mail to Return" or something like that--or maybe someone misreading the name and deciding there is no such person there. So, the best way to find out is by sending another letter and then to wait and see what happens. Good luck....

It sounds like there may have written something in the letter that is a violation of the facilities policies regarding mail. All inmate mail is read and inspected for contraband prior to delivery. Try calling the facility to find out a more specific answer.

Or they have moved from that address and someone returned ti to you

She may have been punished and is not allowed to receive any mail for a while.

Perhaps your letter contained material that is prohibited.

Go to the sent folder if it landed in her spam folder

Maybe she told them to do it.

Maybe someone killed her.