Missing Attachments

Issue reported by user:

A user complains that he receives email from a particular sender with missing attachments. However same email marked to other user can easily access attachments.

Data to be collected:

  • Which email client recipient is using (Outlook Express, Windows Mail, Windows Live Mail)
  • Which email client sender is using (Microsoft Office Outlook)

Troubleshooting Steps:

  • Sent a test email from the sender using Microsoft Outlook and checked the webmail if we can see the attachment there, oh yes the attachment is there. Please see below snapshot which shows entire email including attachments.

Webmail shows attachment is there

  • Downloaded emails in Outlook Express and then checked. The attachment is missing here, rest of the contents of that email is pretty there. Please see below snapshot showing entire email except attachments.

Outlook Express Missing Attachment

  • Saved the email with missing attachment as an .eml file and then opened it with Notepad to check raw contents if it contains attachment MIME code. What I found here is that it contains unknown file “winmail.dat” as an attachment.
Content-Type: application/ms-tnef;
Content-Transfer-Encoding: base64
Content-Disposition: attachment;

eml file opened in Notepad to Study raw contents : Outlook Express Missing Atttachments

  • Here the sender is using Microsoft Office Outlook and by mistake sends email using Rich Text Format (RTF) which is proprietary to Microsoft and used by Microsoft Outlook to send embedded attachments and appointments back and forth. What happens when rich text formatted email received by email client like Outlook Express, it simply doesn’t understand this rich text formatting and simply doesn’t show up the attachment there even it’s there in raw content.


  • The Microsoft Outlook user can send email either in Plain Text or HTML format to avoid missing attachments issue at recipient’s end. In Microsoft Outlook there are three places where you can specify using which format it should send email.
  1. Tools – Options – Mail Format and then select message format from the drop down menu under Message Format section. Set message format to either HTML or Plain Text.
  2. While composing/replying/forwarding an email, go to options and then choose message format.
  3. At contact level also you can use separate message format for each email address saved in single contact. So, say you have a contact named “Gopal Thorve” where you have stored two email addresses, then you can use separate message format for each email address.
  • If you are facing this issue while sending email to particular email address, then I recommend to delete the contact first and then recreate it. While recreating a contact after typing email address in E-mail field double click on email address and select either HTML or Plain Text.
  • Microsoft Outlook also maintains cache of email addresses where you have already sent email but haven’t saved as contact. For those email addresses also you can specify message format while composing/forwarding and after typing email address double click on it and then choose message format using which Microsoft Outlook will send email to this recipient.

Applicable to:

  • Outlook Express
  • Windows Mail
  • Windows Live Mail
  • Mozilla Thunderbird

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