This QuickBooks error occurs when you attempt to write a customer to QuickBooks with an invalid email address.
A common reason that the email address might be invalid is if you copy and paste it from somewhere such as an email message or a web page, which causes it to look like this: "mailto:[email protected]". The "mailto:" gets copied but it is not a valid part of the email address.
Other reasons why the email address may be invalid are that there might be spaces in any part of it ("bob @ example.com"), or no "@" sign (bobexample.com), etc.
Also, sometimes when you copy and paste an email address, it could include some non printable (invisible) characters that render the email address invalid.
To fix this problem, please follow these steps:
Select "Customers" in the ContractorTools main menu, select the customer, edit, and fix the email address. If nothing appears to be wrong with the email address, it probably has some invisible characters in it, so in that case, the thing to do is completely delete it and retype it.
Then select "QuickBooks Sync" in the main menu.
Tap on "Sync Errors". This will take you to a list of the sync errors.
For each error, tap on it, then tap Clear. Or tap "Clear All Errors".
Now go back to the QuickBooks Sync screen and tap "Sync Now". ContractorTools will re-write the transaction to QuickBooks.