It’s actually possible to increase the attachment size limit when you’re using Outlook. By default, Outlook won’t send messages with attachments more than 20 MB in size. But, fortunately, you can inform the mail server’s allotment to send messages more than the default size. You can also keep yourself away from receiving deliverable messages if Outlook’s default is much more than usual.

How the Fix the Error, ‘The Attachment Size Exceeds the Allowable Limit.’?

The steps you should follow depend on the type of the email account you’re using. In short, you should follow a process of modifying the registry. Before moving ahead, make sure you have taken a backup of the registry. Try doing the changes only when you are aware of how the registry would be restored.

For Internet Email Account (POP3, IMAP, HTTP)

Here are the steps to change the limit

Step 1: Exit Outlook and go to the start menu.

Step 2: Press Windows + R to open the run dialog box.

Step 3: Once the dialog box opens up, type ‘regedit’ and click ‘OK’ to confirm.

Step 4: As per the version of Outlook, scroll the registry tree till you find the relevant entry.

For instance, if you’re using Outlook 14.0, locate any one of the registry subkeys as mentioned below.



For Internet email account

NOTE: You should actually create a path if it doesn’t exist.

Step 5: Enter the following registry data in numerical digits against the value name,

‘MaximumAttachmentSize’. The value data denotes the allowable attachment size. For configuring a 30-MB limit, you should specify 30720. Likewise, if you want a file size of around 20 MB, then the value should be less than 20 MB. Never specify ‘0’ as the value since it’s not recommended. The effort of sending attachments would be fruitless and you would get back messages as undeliverables in the mailbox.

For Internet email


Step 6: Finally, exit registry editor and start Microsoft Outlook.

For Microsoft Exchange Server Email Account

If Outlook works with an Exchange Server account, then the limit is configured on the server. So, to adjust the settings, you should go through some steps.

Step 1: Launch Exchange Management Console

Step 2: Once you find ‘Organization Configuration’, click ‘Hub Transport’.

Step 3: Under the global settings tab, go to Transport Settings.

Step 4: Once you view the Actions pane in the section, click on ‘Properties’.

Step 5: Under the ‘General’ tab, modify the value for Maximum send size (KB).

NOTE: Due to cache for different settings, the changes may not reflect immediately. You may have to wait for some hours.

So, hope these way work for Outlook. If you find these useful, then share the information with your friends.