Please describe the problem:
The address auto-fill in the to-field of a new message is too intrusive: when it
finds a match for just the first letter of the address I'm trying to type, it
changes the initial letter to a capital letter and *does not change it back*
when the guess turns out to be wrong. I suspect that aubergine@foo.com is at
least on the specification level if not in practice different from
Aubergine@foo.com, so I keep having to change the addresses back by hand, which
is horribly frustrating.

Steps to reproduce:
1. Add an entry in the address book starting by e.g. A (Anne Jones <foo@bar.com>)
2. Compose a new message
3. Write e.g. the address aubergine@foo.com in the address field.


Actual results:
Now the address reads "Aubergine@foo.com"

The 'a' in aubergine matches with the A in Anne, so the matching is done and
partially undone when I type u (for aUbergine) and the matcher notices it has no
more options left. 

Expected results:
The address should read aubergine@foo.com, as I typed it.

The matching should be unmade properly when the guess turns out to be wrong.

Does this happen every time?
Yes.

Other information: