Real World of Outlook And PST Files: Outlook Attachments Disappear: Recipients Gets Winmail.dat File

"Whenever I send attachments through Outlook, some of the recipient’s complaint that they do not get the attachments while some says that Outlook attachments changed to winmail.dat file. This happens in spite of the type of file that I attached to the message (PDF, DOCX, JPG etc).

However, if I send the same mail through my Gmail account, everything seems okay and there are no complaints. To work around, I turned off the virus scanner, assuming that it might be interrupting and causing attachments to disappear. But unfortunately it didn’t work!"

If the emails are properly sent through web mail clients (like Gmail as mentioned above), then the probable reason could be Outlook message being composed in RTF file format. Basically, web mail applications like Yahoo, Gmail follows HTML as standard for composing mail. There are very less number of email clients that supports RTF format for emails and this incompatibility is responsible for the problem and to prevent winmail.dat attachments from being sent in Outlook, it should be assured that the message is composed on HTML and not in RTF.

What is RTF and HTML War All About?

Basically, there are three standard formats adopted by mail clients to compose a message: HTML, Plain Text, and RTF. If we talk about popularity and number of applications that support HTML standard, they are the highest! While the Plain Text formats holds the second position, very less number of clients support RTF standard to create mail.

There are number of Microsoft’ mail clients that support RTF file format for composing mail. To name a few: Outlook, Outlook Express, Windows Mail, Windows Live Mail. When RTF mail is sent from Outlook to the receiver whose mail client does not support RTF standard, a winmail.dat file is sent along with the message. In such scenarios, the message is incorrectly converted on mail Server resulting to which users may complaint Outlook attachments disappear from the message.

“A winmail.dat file contains details about an RTF message and cannot be opened normally. This is also known as T.N.E.F which means Transport Neutral Encapsulation Format.”

Compose Outlook Message in HTML

Since the trouble is related to RTF format incompatibility, the solution would be to create message in HTML format that is highly supported by number of mail clients. To compose emails in HTML format by default, follow the steps mentioned below:

Outlook 2007 and lower editions:

In the Tools menu>> Options>> choose Mail Format

Outlook 2010 and Outlook 2013:

In the File menu>> go to Options>> Mail and choose Compose Messages in this Format

Compose Outlook Email in HTML by Default

Change Specific Contact Settings

There is a possibility that the contact to which the message is being sent is using RTF as default format for sending message: “Send Using Outlook Rich Text Format”. To check this out, go for the following suggestions:

Outlook 2010:

Double-click on the contact and then double-click the email address. A dialog box named “E-mail Properties” will get opened.

Check out the “Internet Format” section and ensure that “Let Outlook decide the best sending format” is enabled.

Outlook 2013:

In Outlook 2013, switch from People View to List View or Source link to open complete contact.

Double-click on the email address and in the “E-mail Properties” window, check if “Let Outlook decide the best sending format” is enabled under “Internet Format” section.

Outlook Email Properties for Best Format to Compose Message

Convert Outlook RTF to HTML: Internet Settings

Another solution to prevent winmail.dat attachments from being sent in Outlook is to convert RTF to plain text or HTML file format when sending message over internet. This can be done by following means:

Outlook 2007 and Lower Editions:

In the Tools menu, click on “Options…” and choose Mail Format. Select Internet Format button.

Outlook 2010 and Outlook 2013:

Click on File>> Options>>Mail. In the Option group, choose “Message Format”.

Under the section “When sending messages in Rich Text format to Internet recipients” choose “Convert to HTML format”

Convert RTF to HTML/Plain Text for Internet Recepient

Convert RTF to HTML/Plain Text for Internet Recipient

Convert a Message Manually into HTML

To stop Outlook sending winmail.dat file, another idea that can be adopted is to manually convert an RTF message into HTML or plain text.

When you receive an email in RTF format and when you reply to it, the message is automatically composed in RTF file format only. At this point of time if you want to compose a message into HTML or plain text, here are the options to follow:

Outlook 2007:

Click on Options tab and click on HTML button.

Outlook 2010 and 2013:

Click on Format Text and choose HTML.

Convert Outlook Message to HTML/Plain Text

All these tips can help to work around scenarios where Outlook attachments disappear and the recipients receive winmail.dat file instead of original attachments.