Problem emailing invoices and statements through QuickBooks

I can see that you've been through a lot already. I appreciate you for bringing your concern about sending emails in QuickBooks to our attention.

There are a few possible reasons why this is happening:

• The email preference being set incorrectly.
• A damaged QuickBooks installation.
• Domain admin was blocked.
• Account security settings from your email provider.

Since you've done all the troubleshooting steps already. I'll just be sharing some of it to help you fix this. But If you've gone through all the steps mentioned below, I'd recommend contacting us for further help.
First, we want to make sure your QuickBooks Desktop software is in its latest release. QuickBooks periodically provides maintenance release and product (software) updates to fix emailing concerns, add features and enhancements, and update compliance information.
Second, please check the settings in the web mail  preferences:

1. At the top menu bar, Click Edit.
2. Choose Preferences.
3. Click Send Forms on the left panel.
4. Under My Preferences tab, Select the email account you're using.
5. Click Edit.
6. Mark the SSL box, or just select Default.
7. In the Server Name field, make sure the server name matches your email provider's settings.

• If you see mail.yahoo.com for example, change the name intuit.smtp.mail.yahoo.com and click OK.

If you're getting an incorrect password error message, please follow the detailed steps in this article to resolve this: QuickBooks Will Not Accept my WebMail Password.

To isolate this case, we can also send emails using a sample company file to check if it's doing the same thing.

1. Go to the File menu and click Close Company. 
2. In the No Company Open window, click the Open a Sample File button, and choose the sample company file you want to use.

Then, let's set up your email service in QuickBooks Desktop and try to send an email again.
One of our Technical Support Team would also be glad to help you with this. They have the tools necessary to check your company file and help you send emails.

Here's how you can reach them:

1. Go to https://help.quickbooks.intuit.com/en_US/contactus.
2. On the Contact Us page, make sure that your QuickBooks product is selected at the top right corner.
3. Select a topic.
4. Click on the Get Phone Number button.
Please feel free to let me know if you need any help. Take care.

I appreciate you for sharing the result after performing the troubleshooting steps.

Let's do the following steps to isolate this concern for any possible data damage:

1. Create a backup of the QuickBooks Desktop company file
2. Repair QuickBooks
   1. Click Windows Icon
   2. Select Control Panel.
   3. Go to Programs and Features.
   4. Choose QuickBooks.
      1. Click Uninstall/Change.
      2. Choose Continue, then Next.
      3. Select Repair, then click Next.
   5. Once completed, ensure to download the latest QuickBooks release when opening the program.

If the issue persists,  I’d recommend contacting our Technical Support Team. A specialist will look up your account and further assist you via a secured remote access session.

Here’s how:

1. Go to Help.
2. Choose QuickBooks Desktop Help.
3. Click on the Contact us 
4. Choose Search for something else.
5. Type in a keyword about your concern.
6. Hit Submit.
7. Click on the Start a Message

For more insights, you may check these articles:

·         Resolve QuickBooks Desktop performance issues: Manage your data file

Feel free to leave a post below if you have other questions about sending sales forms in QuickBooks. We're always here to help.