Here’s what to do if someone complains that you’re sending winmail.dat attachments with your emails.
The problem is in Outlook and you need to change some settings. The setting might be global for all emails but you may need to check the settings for an individual contact or email address.
Overall Setting
New messages are usually made in HTML format (the default in Outlook these days. That default can be changed at Options | Mail | Compose messages (Outlook 2013 and Outlook 2010) in this format.
Even if you accidentally send an RTF message to an Internet recipient, there’s an option to automatically convert the message to HTML format. It’s down at Options | Mail | Message Format | When send messages to Rich Text format to Internet recipients. The default is ‘Convert to HTML format’.
In Outlook 2007 and before, similar options are at Tools | Options | Mail Format.
Click on the Internet Format button to control how RTF messages are converted.
Individual Recipients
But that’s not the end of the story. Often the winmail.dat problem isn’t caused by the main Outlook setting but the setting for each contact or email address which can be different from the global default.
For an email address in the TO, CC or BCC lines, right-click and choose ‘Outlook Properties’.
It should look like this with the E-mail type being SMTP and the Internet format ‘Let Outlook decide the best sending format’
You can force Outlook to send using either Plain Text or Rich Text format, but not, alas, HTML format.
Strictly speaking an HTML option should not be necessary but it would have been nice anyway.
AutoComplete bug
Sometimes you change the email setting in the Contact but the problem keeps happening. That’s because you’re not using the contact settings for the email address, instead you’re using the autocomplete version of the same email address.
When you type an email address, Outlook will suggest possibilities from your past used addresses.
Click on one of the suggestions to enter the email address.
You would expect that selecting a contact from the autocomplete list would use the current contact email address settings … but it does NOT. The autocomplete list is separate and uses the email settings that apply at the time the entry was added to the list.
To fix this, delete the entry from the autocomplete list (press the black X or highlight the entry and press the Delete key).
Then retype the contact name or email address and press Alt + K. This will resolve what you typed from Contacts and add to the autocomplete list with the newer email settings.
