From one of the last versions on, messages search filter is "accents" sensitive. This is a pain on some languages like spanish or portuguese, since many people ommit accents when typing quickly.
- Searching for spanish word "camión" will not return messages containing the word "camion" and viceversa.
- Searching for portuguese word "camião" will not return messages containing the word "camiao" and viceversa.
Now putting aside the typos of the sender, if I want to search for all messages containing portuguese word "calendário" and also those containing the spanish word "calendario" (note that the same word in one language have an accent and not in the other), I would have to perform two different searches.
This has been discussed many times in the last years and there is an open bug from 14 years ago: https://bugzilla.mozilla.org/show_bug.cgi?id=506064
I think the same is true for other Latin languages like french...
IMHO, accent insensitive search should be a user configurable setting enabled by default.
Thanks for the excelent work you've done with Thunderbird!