Your unique submission email address is the address you use to submit email documents to your account. You can change it from the Settings menu of your account.
1) Login then click on your name/the button with the image of a cog, to the top right of the page. Then select Settings.
2) Goto the Account Settings then select Account Name and Submission Email, then modify the fields under Submission Email Address
The email PIN is a four digit number that you can modify to your liking. We include an email PIN in the email address because this adds an extra level of security. It's harder for non-authorised persons to email the account this way.
Note that your submission email address can be completely different from your account name - modifying one won't change the other.