Wrong addressee, incoming iCloud e-mail

Not spam. The content of the incoming e-mail is legitimate. The issue is this: the incoming e-mail is usually a response to one of mine. The content is, as I said, OK (legitimate). However, the addressee on the incoming address line shows ...@MLB.TV (yes, Major League Baseball) rather than ...@icloud.com. I have a totally separate account (subscription) with MLB.TV that functions as intended, so it seems that somehow that address has migrated to my icloud account/address.

iCloud is in Apple mail; MLB.TV is NOT in Apple mail. The problem only occurs with respect to incoming messages addressed to my iCloud e-mail wherein the addressee reads MLB.TV. I just discovered a bizarre situation when I tried to print one of the incoming messages with the errant addressee; the header format changed, and the addressee read correctly, ...@icloud. I took a screen shot to document the wrong addressee. To be sure I wasn't using an improper procedure, I repeated the exercize three times with different incoming messages, all of which had the MLB.TV addressee (documented by screen shot), but when printed, showed ...@icloud, with no evidence of MLB.TV at all.