Issue
An issue occurs when a user has a personal Google Account with the same email address as their managed Google Account. This causes a conflicting account since they share the same email.
This can happen if a user created a personal Google Account using the domain name of your company or school. If your organization then signs up for a managed Google Account and tries to add those users to your organization's account, they'll have the same address for their personal and work accounts. Two accounts can't share the same email address.
Please see the following example of the error message you may receive:
Sign-in attempt was blocked
your.name%manhattan.edu@gtempaccount.com
Someone just used your password to try to sign in to your account from a non-Google app. Google blocked them, but you should check what happened. Review your account activity to make sure no one else has access.
CHECK ACTIVITY
You received this email to let you know about important changes to your Google Account and services.
© 2018 Google LLC,1600 Amphitheatre Parkway, Mountain View, CA 94043, USA
Resolution
First, you will need to be added to your managed Manhattan College Account using the email address that you used for your personal Google account.
Then, the next time you sign in to your personal account, you will be asked to change the email address associated with that account. You will have the following options:
- Rename the personal account with a new Gmail address.
- Rename the consumer account with a non-Gmail address that you already own.
- Sign in with a temporary username that Google provides (for example, jane%mydomain.com@gtempaccount.com).
If you choose the last option, you will be prompted to rename the account every time you sign in, until you select a permanent solution (new Gmail or non-Gmail address). You will want to avoid this option since that is what causes you to receive the "Gtempaccount" error.
Partially reposted from: About conflicting accounts and Add users who have existing Google accounts