Email Attachments

Attachments are files such as word processing files or spreadsheet files. Attachments are not really part of the email message you are sending, but are attached to it. Attached files are not usually text files like the email message itself, instead they are usually binary files with a specific internal format for a specific software and must be encoded before they are sent. Common attachments include word processor documents, spreadsheets, presentations, and images. Please note that incoming attachments will be located in a separate directory or file system than the email.

When should I use attachments?

Only when necessary. Keep your recipient in mind when sending attached files. They may not be running the same kind of software as you, and handling the attached file may be cumbersome. Attachments usually require the recipient to do something extra to get to the information. Whenever possible, remove the formatting by saving the file as a text file or by cutting and pasting into the message portion of the email message instead of sending a file attachment.

One thing to keep in mind when sending attached files is that attachments will add to the overall size of the email message.  PowerPoint files and other files that contain graphics can add several MB to the overall file size of the email message.  

Here are some examples of when it is appropriate to send a file attachment:

  • When the file needs to be edited by the recipient and returned to you in the original software format.
  • When the recipient is not on the same file system/server and cannot access the file directly.
  • When the content of the file is formatted in such a way that cutting and pasting is either too cumbersome or the content loses meaning with the formatting.

What do I need to know about file extensions?

Most software (word processing, spreadsheets) allow you to save a file in different formats. You should always choose a format that is compatible for your recipient.

Here are some common software applications and the associated file extensions:


Software Application File Type File Extension
Text editor / word processor Plain text .txt
Word processor Rich Text Format .rtf
Adobe Acrobat Portable Document Format .pdf
Microsoft Word Document .doc
Microsoft PowerPoint Presentation .ppt
Microsoft Excel Spreadsheet .xls
Macromedia Fireworks Graphic .png
Adobe Photoshop Graphic .psd
Web-friendly image Graphic .jpg, .gif, .png
Web Page HTML .htm, .html