occasional problem with email sent to my iCloud account

I have a Mac desktop and several Apple devices. I keep the software on all of my devices current. I use an iCloud email account and the Apple mail app. My problem: Several friends and a number of business contacts complain that when sending an email to my @me.com email account, the email is undeliverable. One financial institution has had this problem happen at least 6 times in the last couple of months. I'll confirm my email in my account profile, will receive an email to the @me.com account, and then 3 days later, I'll receive a letter via snail mail notifying me that my @me.com email account isn't working. And this seems to be happening more frequently now.

I am not aware that any email I sent has not been delivered. And I tried checking iCloud Status, but I have no way of knowing when someone sending me an email experiences the bounce.

Any ideas on how to address this?? It's happening too frequently with diverse people/businesses...