Send Mail: Code: ErrorIrresolvableConflictMessage: The send or update operation could not be performed because the change key passed in the request does not match the current change key for the item.
Note: This is a known issue and it is going to be resolved in the Office365 activity package version 1.15.0.
To be able to see these packages,
- Go to Manage Packages
- Select the Office365 package
- Check the option "Include Prerelease" (as in the example below)
- Upgrade the package to a version over 1.15.0.