Written by Support InfoBridge
In the Google Synchronizer you have the option to have the users authorize the Google Synchronizer themselves. This method is explained in this KB article.
If a user changes his password the authentication is lost and the calendar of this user is no longer in synch. You will see erros in the logfile like this
Unable to register user: John Doe error: DotNetOpenAuth.Messaging.ProtocolException: Error occurred while sending a direct message or getting the response. ---> System.Net.WebException: The remote server returned an error: (403) Forbidden.
In Situation A you can use the Token Manager to send out an email to the user(s)
In Situation B you can use the re-authenticate option to send an email to the user(s)
The mails are send using a 3rd party tool called Send Grid. Sometimes the mails will get bounced and the authentication mail does not arrive at the user(s)
The issue is described here: https://sendgrid.com/docs/ui/account-and-settings/gmail-dmarc/
The best solution is to use a different FROM address, no gmail address. For example: firstname.lastname@example.org