I've had numerous occasions where I won't get mail for a few weeks, and then I'll get slammed with hundreds all on one day.
I notice that it'll happen once I start getting a serious reduction in my daily e-mails. I'm right in the middle of one of those periods now.
I've turned off all my spam filters for a week now, and no difference.
I know I'll get hit any day now with tons of mail, spam and otherwise.
I'm trying to run my website and the e-mail address I use is my business e-mail and it's getting bad enough that I'm losing business, and I'm looking to find another host for my site.