How Many Megabytes Can I Email From Outlook?

Before sending an email from Outlook, you need to know your ISP's megabyte limits.

Outlook is a stand-alone email application for Windows systems that lets you send and receive messages as well as keep track of appointments and errands. The application is capable of accepting and processing emails from multiple Internet Service Providers (ISP) as well as Internet-based email services. But when sending emails from Outlook to other recipients, you must conform to message size limits, also known as megabyte (MB) limits.

Megabyte Limits

Megabyte limits are set by your Internet Service Provider (ISP) and not by Outlook itself. If you send an email that exceeds your ISP's server megabyte limit, the message will be returned to you as a bounced message, and not delivered. You must remove any attachments, embedded images or other data from the message before you attempt to send it again. ISPs may set a megabyte limit anyone from 1MG to over 1 gigabyte, or GB, depending on the server size and type the ISP uses. Your ISP's megabyte size limits are included in the documentation that was sent to you when you signed up for the Internet service.


If you're adding an attachment to an Outlook email, reduce the size of the attachment as much as possible. For a picture or chart, use a graphic manipulation program to reduce the size. Limit your attachment size to under 2 MB, especially if using a dial-up or slower speed ISP. Even if the text portion of your email message is small, a large attachment will stop the message from sending.

Outlook's "Sent" Folder

Repeatedly trying to send messages that exceed your ISP's megabyte limit can result in overloading Outlook's "Sent" folder. This can cause the email application to crash if you don't manually enter the folder and delete the sent emails. To delete, double click the "Sent" folder and click on the first message in the folder. Press and hold the "Shift" key on your computer's keyboard, then click the last message in the folder. All of the messages in the folder will be highlighted. Press the "Delete" or "Del" key to remove the sent messages. If you want to pick and choose which messages you want to delete, press and hold the "Ctrl" key on your keyboard and click the messages you want to delete. Press the "Delete" or "Del" key to remove the messages.

Errors and Notifications

When a message exceeds your ISP's megabyte limit and is sent back to you, an error report is also sent, informing you of the megabyte size limit. The report is part of the returned message and doesn't require a reply. Delete the message, with the attached error report, and open your original message to reduce its overall size before resending.

references & resources