E-mails sent from Mail app show icloud.com instead of me.com

I jumped on board the Apple bandwagon, shortly after .Mac.com was "reskinned" as .me.com, which of course was again "reskinned" as .icloud.com.

My contacts know me via my me.com e-mail address.

My iOS devices are configured to "advertise" my me.com e-mail on outbound messages, which I can see in the Mail app when composing messages.

In the last week or so, I have noticed a rash of issues where my e-mails appear to the recipient as having come from my @icloud.com address. This causes confusion and actually causes my e-mails to be missed, because the recipient doesn't have my @icloud.com address in their white list. I am not able to remove icloud.com address from my reachable addresses in my mail settings -> accounts -> iCloud. There is a note there about changing the reachability in Messages or FaceTime, instead, but I don't have my icloud.com address listed as reachable there, either.

I am having a very similar issue with a completely unrelated mail service where I have two different addresses on the same mail server, and even though I have chosen address "A" for the from, the mail is received as though sent from address "B." I can confirm in the Mail app that I am composing the mail showing my from as address "A" but the recipient sees address "B" and even in my sent folder it's stored as address "B." Address "A" is checked as the default, so it's very strange that any e-mail would go out from address "B" without me explicitly choosing address "B."

I have deleted address "B" and saved the settings, then re-added it and even changed the order of the listed addresses around. The only workaround that is effective is to completely delete address "B" and then only re-add it when I need to send from that address, which is thankfully somewhat rare.

But for the icloud.com address I can't find a workaround and it is breaking my ability to participate in groups.google.com and a number of ListServ type groups, because I am registered via me.com and they are receiving the e-mails as though sent from my @icloud.com.

I am thinking these issues are all related, but I can only control the .Mac.com / .icloud.com behavior, so I am hoping the community will have a workaround for the .iCloud.com behavior.