How to Send Large Size Email Attachments in Outlook

Microsoft Outlook limits the size of attachments to 20mb (20480kb), this isn’t an issue if you’re sending a document or a picture, but if you’re sending a set of large high-res pictures, larger files, or even videos, this can become a major hindrance. This applies to one large file or several smaller files that combined exceed the size limit. If you attempt to send a file that exceeds the size limit, you will receive this error message: “The attachment size exceeds the allowable limit”. This error message wasn’t added until Outlook 2010. If you have an earlier version of Outlook you may receive a different error message from the mail server.

There are several methods that can be used to work around this problem. The easiest fix is to resize the attachment or compress the file. Multiple files can be compressed into a zip file to reduce the overall file size. This, however, doesn’t work for everyone’s situation. It may be necessary to increase the limit allowed by Outlook as well.

Depending on the limit set by your email provider you may be able to increase the Outlook limit to match. This involves going into your computer registry to alter the limit set by Outlook. The following directions will walk you through changing the registry to increase the limit size in Outlook.

How to Increase the Attachment Size Limit in Outlook:

    • Click the Start Menu and type “regedit” into the search bar.


    • The search result should now show Regedit under programs. (Windows XP users will need to select RUN from the start menu and then search for Regedit).
    • Use the registry tree to follow this path: HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences.


    • Click the MaximumAttachmentSize key if available. If you do not see the MaximumAttachmentSize key, then you can manually add the entry.
        • Right click in the middle of the screen to open the menu.
        • Select New and DWORD Value.


        • Set the name as MaximumAttachmentSize.


      • Press Enter.
    • You can now change the attachment size limit. The value must be in kb. (Example 25 mb = 25600kb) The value you use should be based on the file size limit allowed by your mail provider.


  • Click OK.

Most email providers limit combined email file size to 25mb. This can be a problem if you need to send an attachment that is larger than the allowed size. This registry tweak is only useful if your email provider has a larger file size limit then the Outlook default limit. Another option is to turn to downloadable add-in programs. There are a variety of add-in programs that will allow you to compress and send an attachment. The down side is the person receiving the attachment is required to download or access the program as well to be able to open the attachment.

File Sharing Web Services

Many web-based clients have started providing ways to send larger attachments. Yahoo! using a built in Dropbox interface and Gmail which uses Google Drive both allow users to send larger attachments via email. Once your recipient receives the email they are able to access the attachment without downloading any software or logging into any other sites. Microsoft also provides a free on-line storage service called SkyDrive for sharing larger files. The files are password protected and can be shared with anyone you give access to.


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