We've got several accounts running on Gmail / Google Apps for Business—these accounts have been alive for about 10–12 years (running on a different email provider). Because they've been around for so long they are on tons of mailing lists, and junk lists.
I’ve unsubscribed from a load of lists using unroll.me but we still get loads of junk messages through, which go to the spam / junk folder.
The only problem with this is that some proper email goes to the junk folder, which we don’t look through as there is so much in there. I don't mind proper emails being in there (although it’s not ideal), my main concern is I heard Gmail auto deletes the spam / junk every 30 days so we would have no record of the proper emails in there, which we really need. Is there any way to stop Gmail auto deleting the spam?