the thread reached the limit for posts so it was locked and a new one started. The FAQ should have been kept as the first few pages but either the admin or robot who did it did not take that into consideration.... anyway i copied and pasted it for you:
15. Inbox & Banking
If you’re curious to know how to ‘bank’ or just forgotten how to, your answers can be found here. Information on what your inbox does can be found here too.
How long do items stay in the inbox? Do they expire after a set time?
How long does stuffs inbox stay for? Forever or do they disappear after a month or so?
Spoiler:
(zoebeagle)
It’s forever and no. Also, there is no limit to the amount of items in your inbox.
(po1102)
According to in-game FAQ, stuff in inbox never expires.
Anyone know what the limit is on the Inbox?
Spoiler:
(Callanthe)
The inbox is infinite. However, any items past 1000 will be hidden and not directly accessible.
I keep seeing the idea of banking. What is it exactly?
Spoiler:
(profile4)
Keeping money/units in your inbox so that it doesn't get stolen/keep room for enhancing, trading, or whatever.
How does one "bank" their luna?
Spoiler:
(clocksprocket)
Luna in your inbox is safe from any attackers.
What you can do is have someone help you bank --
You start a trade with them with the amount of luna you would like to bank, and have them send you back the same amount. When you accept the trade, you'll both get that amount in your inbox.
Alternatively, you can send a trade to a friend with the money and just have them cancel when you need your money back (it goes immediately to your vault from a cancelled trade, unlike cards which will go to your inbox) but this requires them being online when you need money, so preferably they'd be someone you can contact quickly.
What's the limit of cards you can have in your inbox? I'm supposed to have more than 1,000 cards in it (a lot of feeders), but the notification keeps flashing just 1,000. Does it push out the oldest cards after the 1,000th or is the notification just set to display at 1,000 maximum?
Spoiler:
(larrydust)
Although your inbox can hold more than 1000 items, only the most recent 1000 items can be displayed. If you remove items from your inbox, your additional items will start to appear.