Over Quota error persists despite archiving in Lotus Notes

I continue receiving Over Quota Error warnings and was told by colleagues that e-mails sent to me are still bouncing back despite my mailbox's free space.
I have archived my older e-mails as per a colleague's advice. I was told that this will free up my mailbox space without having to delete any correspondence.
I do not understand why lotus notes is still telling me that my mailbox is full.
What do i do?
