Here's an example sequence of emails from a sender and recipient perspective.
SENDER sends out an email with a trigger to encrypt the message (using the word [encrypt] in the subject line in this case but you would get the same effecting using our SpamReporter plugin encrypt button).
SENDER receives a notification that the email was sent in encrypted fashion.
RECIPIENTS gets a notification with a one time code to access their email.
RECIPIENT accesses the web portal and is asked to submit the One-Time code and then click view the message
RECIPIENT User is now in the portal and can view the message, reply or forward
If the user wants to view the email at a later date, he can go back to the original reception notification, click "view secure message" and he will be re-issued a new code.
Conclusion - no more messy login or sign up.
Also, the sender will receive a read receipt.