Often when I'm typing in someone's name or email Thunderbird will autosuggest several similar names and, if the contact has emails at multiple domains, all those domains will be suggested. The problem is, for many of my contacts, I don't remember which domain(s) they're currently using. If Thunderbird kept track of the last time we received an email from each contact address, it could display an autocomplete list like:
Input: John D
Suggestions:
John.Doe@email.com (last used 2023-5-25)
John.Doe@hotmail.tv (last used 2017-2-3)
John.Dozer@example.com (last used 2023-1-3)
If I was looking for John Doe, this would let me easily pick the email.com address as the current one.