Error: Password is not IMAP convertable, but can skip it

[LinqLover]

Steps to reproduce:

• Login with a password that contains a quote (")

Expected result:

Login successfull (provided that you entered your real password).

Actual result:

Error: is not IMAP convertable [sic!].
But I can skip this error (Proceed) and the authentication is successful.

[laugengebaeck]

See also #258.