Winmail.dat received ONLY when an invoice is sent in bulk

Thanks for reaching out to the Community, RJ4242.
 

When an email recipient receives an attachment called Winmail.dat instead of a .pdf file for their invoice, this is a known issue for Microsoft outlook if the recipient's email client isn't capable of receiving rich text format.
 

If only one or some customers are experiencing this, it can be due to a problem on the receiving end. Certain security and mail filters may detect these emails as mass emailing. This can be fixed by adjusting your message format accordingly in Outlook. Be sure to choose HTML or plain text to prevent Outlook from attaching a Winmail.dat file when sending the email. You can find detailed steps for changing these settings on Microsoft's website.
 

Your other option is to use an email service other than Outlook when sending emails from QuickBooks.
 

Please don't hesitate to send a reply if there's any additional questions. Have a lovely day!

I have researching this Issue for years.  It is got to be a known issue, and it is disappointing to see a solution to “use a different email provider.”  The problem is Quickbooks, unfortunately. I have QuickBooks Desktop P ro 2024 subscription.  It is further disappointing to read that this also exists in Quickbooks Enterprise, my only upgrade path forward.

I am an old software engineer, familiar with HTTP and SMTP protocols. I send hundreds of bulk invoices.

This is the pattern:

1. The issue only occurs during bulk email 
2. Manually sending the same invoice from QBPro24, or even forwarding the outlook email from the Sent Items folder, will deliver it with no problems 

3.All affected users have a Mac

4.When the bulk email function composes each invoice email, the formatting of the recipient is as follows:

‘[email address removed]’ <[email address removed]> 

5.This header is different when Outlook sends it.

Observations:

The first part is the “display name”.  This is not required, but you may notice that I used apostrophes above. That is what Quickbooks puts there. This is not standard. The Internet standard appears to be quotation marks for the display name. I’m wondering if this is the issue, that Macs do not know how to resolve and subsequently fail at translating the PDF, instead turning it into a winmail file.

It may be useful to not use the display name at all.  The email address must be in greater than/less than brackets.

My workaround is to flag those customers that are affected with a note in their customer name, and manually sent those emails. This is very time consuming.  Unfortunately, the only way I’m aware that a customer  is affected is when they  tell me they cannot open the invoice, which is embarrassing and unprofessional.

My only hope is this can somehow get to the development team and made a priority for thousands of loyal users that are affected.