Mail sends messages from wrong account

Normally when I send new messages they are sent from my .mac account as configured in preferences. But sometimes emails I send go out using a different email address (a google account I use for a community group I belong to). When that happens, I use the pull-down menu in the From: field to change back to my .mac address and none of my iCloud addresses appear on the list of available accounts. If I quit Mail and restart it, then all available email accounts show up again in the pull-down menu. So I have a stopgap solution - quit and restart, but it's a pain in the *** to do, and often I don't catch it before emails go out from an address my correspondents aren't expecting.

Has anyone else had this problem and found a way to fix it? Thank you in advance.