No. Email messages are transferred by mail exchangers by hopping from server to server until the message is delivered to your mailbox.
The outgoing mail server (SMTP) of your email application only encrypts the first hop. This is a very good thing because is protects your password which is only transmitted on the first hop. However, your message may not be sent encrypted on all the remaining hops. Also your message might be stored unencrypted on any server it is processed by.
To keep your message private from end to end, both the sender and the recipient must install a client security certificate and send the message as digitally signed and encrypted.
