It is not using the email addresses you enter for the individual people whose returns you are preparing. So, no, entering different email addresses for them will not let you e-file more than five federal returns. If you have more than five returns to file, some of them can be filed by mail.
Not sure what you think "registering" with the IRS means. If you have the credentials to use professional tax software you can purchase and use that software, prepare tax returns for as many people as you want, and e-file them. But you cannot use ordinary TurboTax for more than five federal e-files; paid tax preparers---or even generous people preparing returns for family members -- cannot get around that IRS limit with TurboTax.
From IRS PUB 1345 —- limit of 5 e-files
https://www.irs.gov/pub/irs-pdf/p1345.pdf
This appears on page 36
Additional Requirements for Participants in Online Filing
In addition to the above, participants in Online Filing must adhere to the following:
- Ensure that no more than five electronic returns are filed from one software package or one e-mail address.
- 2. Supply a taxpayer with a correct Submission ID.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
