When typing an email address, the address input field behaves like expected. But when I click somewhere other than the end of the inputted text, just one character is inserted there, then the cursor jumps to the end of the line.
E. g. when I have "email@address" and set the cursor to the beginning of the line edit (to type the name and < and >), I get "Semail@addressome Name <", the "S" is inserted correctly but the "ome Name <" goes to the end.
Still present in 4.12.1.
*** This bug has been marked as a duplicate of bug 318597 ***