We’re starting to see reports that begin something like this: “We’re using a sendmail server. When we use Outlook 2010 and try to send attachments over 20MB we get an error: “The attachment size exceeds the allowable limit”. This works fine under Outlook 2003.”
The default limit is 20 MB (20480kb), which is about right for most ISPs. This limit eliminates the problem with stuck messages: If you try to send a message using SMTP, you get an NDR back into your Inbox telling you the message is too large. Outlook wastes a lot of time uploading the huge file that will never send and this prevents the sending of any other mail.
Exchange server accounts should use the message size set for the user account. Exchange 2010 users will see a mailtip above the To field instead of the warning dialog.
If the MaximumAttachmentSize is set higher on the client than the Exchange account is allowed to send, the message will not send. The Send and Receive Progress Dialog will show this error:
Task ‘alias@domain.com – Sending’ reported error (0×80040610) : ‘The message being sent exceeds the message size established for this user.’
If you can send larger attachments you can edit the registry to allow larger limits. While you can set it to 0 for unlimited message size, its better to set the limit to the size your ISP allows.
[Click to view larger image]Open the registry editor and browse to:
Outlook 2010:
HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences
Outlook 2007:
HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Preferences
Then add a new DWORD value: MaximumAttachmentSize
Unlimited message size uses a value of 0. For a specific message size (recommended) enter the value in Kb. You may want to round the value down to allow for overhead, so 50MB = 50000.
If your mail server limits you to smaller attachment sizes, you can set the key to prevent an NDR when you attempt to send messages that are too large.
Instant Fix
You can can change the dword value in code below if needed (its set for 30 MB) then copy and paste into notepad and save as “MaximumAttachmentSize.reg”. You’ll double click on the saved file to install it in your registry.
Windows Registry Editor Version 5.00 [HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Preferences] "MaximumAttachmentSize"=dword:00030000
Download a ready-to-run registry file to set the maximum attachment size to 30 MB attachments
Outlook 2010
Email Compression Tools
If you use tools such as WinZip’s Companion which compress large attachments automatically after you add them to the email message, you’ll want to set the maximum allowed size at least twice as large as allowed by your email service, or set it to 0 to disable completely. Outlook checks the attachment size as soon as you add the attachments, not before you send the message.
More Information
Compression Tools for Exchange server
Compression Tools (for Outlook)
Outlook 2010 and Large Messages (Outlook Tips)
Outlook 2010 attachment size limit (Technet forums)
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Last reviewed on Mar 7, 2012
Am 70 years old, so don’t expect you are talking to a peer. For the first time in many years, on Outlook 2010 only, my attached PDF files are shrunk. When I click to open, it looks like the doc is about 70% of normal. When I print, it is still about 70% of normal. It says in the tag that the size was reduced for email, but my son guarantees that has nothing to do with printing a form and seeing teensy print and white space for the first 25% of the paper (top). I can’t find any “help” for this! Answer if possible pretty please!
Outlook didn’t do it. :)
What PDF application do you use? I’l see what i can find out – i’d never heard of pdf’s getting shrunk for email.
This is sad. Back when we all used unix there was a “Split” command that would break up a file into small chunks and the email on the other end would re-assemble. We are slipping backwards it seems.
Outlook no longer includes the ability to split files (since Outlook 2002) because, as mailbox and allowed attachment sizes grew, very few people used it and too many people had no idea how to put the attachment pieces together, generating a lot of help desk calls. Zipping files to reduce size is often better, or use an online file storage system and send a link… or split them outside of Outlook- I think winzip can still split files.
If you receive a split file, Outlook should be able to put it together.