Until you are at the AME and surrender the confirmation code (remember DO NOT do that on arrival), the information in the MedXpress system isn't "live" yet.
Per Dr. Bruce, if the information is not accessed by the AME within 30-60 days of you submitting into MedXpress, the information is deleted by the system..
There is no penalty to having multiple email accounts within MedXpress. However, hang on to the email you do use to fill out the questions. If you use that email account when you apply for your next medical, many of the personal information fields will already be filled out for you.
What the FAA was referring to is if you had handed the code to the receptionist and she had captured the online data with that code and printed off the form. The form and application is now LIVE and only the AME can make changes and/or fix small errors.
One last piece of counsel --- do not be going into your exam unless you know with greater than 100% confidence that you are going to pass and do not have any health gremlins lurking about (high blood pressure, cardiac issues, high blood sugars, etc).
Once the form is "LIVE", the AME and the FAA can only approve or deny, there is no middle ground. They may set up a very short deferral period to permit gathering of records, but this still is setting up the approval or denial decision. And you do not want to get denied.
Again, don't surrender the confirmation code given to you by MedXpress and printed at the bottom of the PDF and go "LIVE" until the AME says he will issue the certificate. Retaining the code in your pocket or wallet keeps the office visit in "consultation stage", which is not reported to the FAA. So if something is discovered, you have a change to handle it and return at a later date.