Using Office365, you can send an attachment from either your local computer or from OneDrive.

An e-mail attachment is a file that is attached to an e-mail message. For example, you may attach a graphic, a spreadsheet, or a word processing document.  Sending attachments can be a good way to transfer a copy of a file if the sender and recipient have agreed on a format. This is easy if the same hardware and software are in use. However, differences in the computer platform being used (Windows, Mac, UNIX) and differences in versions of software can result in a failed message.

Tips For Sending Attachments

When you aren't sure, send "basic" attachments

 There are many types of attachments that can be sent via e-mail; however, not all e-mail systems handle attachments in the same way. If you are not sure what types of files your recipient can view, it is a good idea to use one of the following file types to send your attachment.

  • Plain text -- save your file without formatting options such as bold and underline. All word processors and text editors should be able to read a plain text document.
  • RTF -- Rich Text Format is a document format that is readable by most word processors. The RTF file is a plain text file representation of a formatted document.  RTF includes codes that the recipient's word processor uses to recreate the formatted document.
  • PDF -- Portable Document Format -- is a file format that preserves all of the fonts, formatting, colors, and graphics of a document..

Specify what software and version was used to create the attachment.

If you have communicated ahead of time with your recipient and know the types of files they can view, then it is fine to send a Microsoft Word file, a picture, or a spreadsheet. But, if the person you are sending the attachment to is using an older version of the software, they may not be able to view it, so it is helpful for them to know the version of the software. For example, you receive an Excel spreadsheet that was created with version 2013, but you have Excel 2007 installed on your computer; or you have Word 2013 and the file was created in WordPerfect, you may need to tell your software what to convert from.

Don’t send attachments to e-mail lists.  

If you wish to share a file with members of a departmental e-mail list (e.g., abc staff), please do not send it as an attachment. This causes the file to be copied many times (once for each list member), which causes heavy traffic on both the network server (or user's hard drive) and e-mail server. The best way to share a file within your department is to store one copy of it in the "shared" area on the network server (L:\Shared) and refer to it in an e-mail note.

Limit the size of your attachments

When you send an attachment be aware that the recipient may have a limit to the size of the attachment they can receive.  Office 365 has a maximum send and receive message size (and optional attachment) set at 25 MB.  Also, when you attach a file to a message, the file size of the attachment increases (it can increase as much as 30% in size).   Keep in mind that someone's mailbox on the Office 365 server will be prohibited from receiving messages if they exceed the maximum quota limit.  The default maximum quota for receiving is 50 GB.

If you need to send the same document multiple times, change the name each time

Multiple versions of the same document can become confusing and occasionally you might send a different version of the document than what you had expected. A better way to manage multiple iterations of the same document is to change the name each time by adding a revision date and/or time to the filename. That way, each document name will be unique and it is easy to tell by the name, which version is the most recent.  Then the older versions can be deleted.

Tips For Receiving Attachments

Do not open an attachment if you don't know what it is

Use caution when opening attachments that you weren't expecting or that you don't know the content. Many computer viruses are sent via e-mail attachments and can damage your computer. If you receive an attachment - especially a .exe or .vbs - and you aren't sure what it is, you should run your updated virus software before opening it.

Clean up your attachments regularly

It is a good idea to clean up your attachments on a regular basis (e.g., once a week, twice a week, etc.). If you don't, your hard drive, your mail server or your network server will become cluttered with old attachments and take up valuable storage area. Some e-mail programs have options to automatically delete your attachments when you delete the message - check your particular program to see if this is available.

Common Attachment Types and Extensions (note that some of these extensions could be blocked if you try to send them via email)

Document Type                  Extension

Microsoft Word                   .doc or .docx
Microsoft Excel                   .xls or .xlsx
Microsoft Power                  .ppt or .pps
Word Perfect                       .wp
Text only                             .txt
Rich text format                   .rtf
Portable Document format   .pdf
GIF Graphics                        .gif
JPEG Graphics                      .jpg
HTML Files                            .htm or .html
Self-extracting Archive          .sea
Executable Files (Windows)  .exe (only open if you know what it is)
Visual Basic Script                .vbs (only open if you know what it is)

  1. Click New in the upper left hand corner to start a new message
  2. Click the paper clip icon to Insert

  1. Choose attachments or OneDrive files
  2. Click Computer -- This will allow you to search your computer for the file you want - you can choose your C: drive, H: drive, L: drive, etc.

  1. Find the file you wish to use, select it and click Open

  1. Select "send as attachment"
  2. You will see your attachment in the email below the subject line

A new feature is available in Office365 OWA. Users can now attach files stored in their OneDrive account. The process is not too different from attaching files normally. The key difference is that files shared via OneDrive can be edited by other users and used for collaboration. This feature cannot be used in Outlook presently, only OWA.

  1. When sending a message, click "Insert" near the top where the options are displayed
  2. From the drop down menu, select "Attachments or OneDrive files".
  3. A window will appear where you will be able to indicate where the file is. Two places are presented to the user, one is OneDrive and one is Computer. Choose any file from any folder inside OneDrive and then click Next..
  4.  Select Share with OneDrive. 
  5. After attaching a file,  select the "..."
  6. Select Manage Permissions from the drop down menu
  7. This allows you to select Can Read or Can Edit permissions. You can also select "Apply to All Attached Files" if you are attaching more than one file.
  8. Click OK

Changes that other users make on the file that you shared via OneDrive will also reflect changes in the file in your OneDrive folder. If you do not wish to collaborate your work, set "Read only" permissions before sending it, or attach the file from your computer.

The Office 365 server has the maximum send and receive message size (and optional attachment) set at 25 MB.

Keep in mind that someone's mailbox on the Office 365 server will be prohibited from receiving messages if they exceed the maximum quota limit.  The default maximum quota for receiving is 25 GB.  Also, when you attach a file to a message, the file size of the attachment increases (it can increase as much as 30% in size).

If you select the "Rich Text" message format, the attachment icon displays in the message itself, instead of in the message header. One of the main reasons for designing Rich Text, with the attachments in the message body, is for ease of adding descriptions when sending e-mails with multiple attachments. For example, when the attachments are embedded in the message body, it's easy to add an attachment description, then the attachment below and so on.

Article number: 
103580
Last updated: 
June 9, 2016