Problem: Quickbooks couldn't add my receipt to my account that i forwarded via my email. Reason of failure provided by quickbooks: Your email was marked as spam. help?

Welcome to the QuickBooks Community, @ovalsplints-gmai.

Helping you to finish your QuickBooks Online (QBO) tasks is our priority. To isolate the issue, let's first check the customized email. This should end with @qbodocs.com.

Let's also confirm the email address you're trying to enter is from QuickBooks Online (QBO) users. To allow users to send receipts or bills, they need to have Standard user access with vendors' permission. To further look into it, you can go to the Manage Users page. Here's how:

1. Sign in as the Master Admin of your QBO account.
2. Then, click the Gear icon and choose Manage Users.
3. Select the Edit button to check each user's email address.
4. If you can't find the email address, select Add user.
5. Choose a user type. Then, click Next. Note: Some roles count toward your user limit.
6. Pick the access rights for the user and then, click Next. 
7. Input the user’s name and email address. Then, select Save.

When done, go back to the Receipts window and add the email address. Then, to further guide you in emailing your receipts to QBO, please see this article: Email receipts and bills to QuickBooks Online.

You can also reach out to our Customer Care team to further guide you in performing any QBO tasks. 

Don't hesitate to come again here if you need further assistance looking forwarding your receipts in QBO. I'm always here to lend you a hand. Keep safe.