I just noticed this behavior: my wife has two email addresses I write to frequently: email@example.com and firstname.lastname@example.org. I have both addresses in her contact named “Jane Doe.” I do not have a nickname of any sort. My son has her gmail address as “Mom” in his contacts, and messages from him to both of us show “Dad” and “Mom” in the headers.
Then when I compose an email to my wife, it shows “Mom” in the header if I pick the gmail address. Her gmail address won’t even show up if I spell out “Jane Doe,” although once I type “email@example.com” it displays “Jane Doe <firstname.lastname@example.org>” as an option. then when I choose the name, it renames it to “Mom” again. I understand that incoming names are defined by the headers, but how is eM Client grabbing my wife’s nickname from a different sender when I compose one to her (not a reply or reply-all, just a new message)?