When replying to an email, if the FROM header in the original email has the name quoted, the name is not stripped out and you have to manually strip away everything except the email address in order to send.
e.g.
From: Name <test@test.com>
Will be okay and the recipient will be just the email address test@test.com
Where as
From: "Name" <test@test.com>
Will display the whole string "Name" <test@test.com> as the recipient and sending will fail email address validation