I use Outlook Express. I cannot advise you about any other email program. I would think that they would have similar problems.
I only have 3 gb and that is over 10 years of business emails. That is a lot of emails.
If you don't have a lot of emails, you should to compact the messages and remove attachments.
If you have a large amount of messages in one folder, dividing them up into smaller folders should also help.