Using Microsoft 365, you can send an attachment from either your local computer or from OneDrive.
An email attachment is a file that is attached to an email 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) and differences in versions of software can result in a failed message.
The Security Office also has a list of Best Practices for Email Attachments
Tips For Sending Attachments
When you aren't sure, send "basic" attachments
There are many types of attachments that can be sent via email; however, not all email 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.
- 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 2016, but you have Excel 2010 installed on your computer; or you have Word 2016 and the file was created in WordPerfect, you may need to tell your software what to convert from.
Don’t send attachments to email lists.
If you wish to share a file with members of a departmental email 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 email 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 email 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. Microsoft 365 has a maximum send and receive message size (and optional attachment) set at 150 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 Microsoft 365 server will be prohibited from receiving messages if they exceed the maximum quota limit.
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 email attachments and can damage your computer. If you receive an attachment 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 email 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)
- Click New Email in the upper left hand corner to start a new message
- Click Attach file (paper clip icon) to attach the file
- Select the location to find the file to attach (C: drive, H: drive, OneDrive, etc.) --
- .Find the file you wish to use, select it and click Open
- Type the text of the message and click Send.
The Microsoft 365 server has the maximum send and receive message size (and optional attachment) set at 150 MB.
Keep in mind that someone's mailbox on the Microsoft 365 server will be prohibited from receiving messages if they exceed the maximum quota limit. 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).
- Login to Microsoft 365
- Click the Outlook icon
- Click the Mail icon
- Click New
- Click Attach (paper clip icon)
- Choose the location of the file (C: drive, H: drive, OneDrive, etc.)
- Select the file name and click Next.
- On the "How to share this file" screen, select how to share the attachment -- share as OneDrive link or Attach as a copy.
- Click Send.