Don't believe this is a repost and may be working as intended. When you're at the BG mark limit of 100 marks any subsequent marks you earn are then mailed to you. These marks received in the mail used to expire within 24 hours, which wasn't very helpful if you were only capped in one type of BG mark and doing Concerted Efforts turn-ins. Recently I noticed that these mails act like regular mail and expire in 30 days rather than 24 hours. As this season is drawing to a close and next season starts soon, it is now possible to stack marks past the cap to buy up all the season 8 off set pieces right away.