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Friday, July 14, 2006

Microsoft Exchange/Outlook Attachment Size: Best Practices, Limits, and Solutions

Summary: 5MB is the effective [email attachment] size limit cited as examples for Microsoft Exchange/Outlook on Microsoft Support. How to send large email attachments through Accellion SFTA without causing Exchange/outlook problems.


"Massive email accounts [are] killing our [E]xchange server" -- Louise H.

This was an actual quote that I got earlier today from an IT officer who requested information on Accellion's Courier Secure File Transfer Appliance.

I recall reading an Osterman Research study where 80% of the email traffic is in attachments. All these attachments end up at somebody's email inboxes. The trouble is that when these email accounts get too big - they can crash email servers.

Adding to the woe is the degradation of network performance when an email with a 15MB attachment is sent out to 20 recipients (spiking the effective email attachment load to 300+ MB with one click). While all those bits and bytes are making their way through the network, the entire email system will come to a near stand-still.

There are very few things that IT does that would get the CEO's attention immediately. But, trust me, when the email server crashes or when the email/network is crawling, the CEO will notice.

Fun, huh?!

That is precisely why IT uses attachment size limit settings in the email server.

The trouble is that there are legitimate cases where large files need to be shared and attachments via email is the most intuitive and convenient method for both senders and recipients. (Lawyers and advertising curative teams come to mind.)

I was recently told by a reseller who specializes in Microsoft Exchange/Outlook implementations that the Microsoft Exchange 2003 best practice for maximum email attachment size limit is between 5MB and 10MB. Consequently, they are using Accellion SFTA to complement their Exchange/Outlook deployments so that the users can have a high-performance email infrastructure while preserving the ability to send very large attachments as part of the everyday business process.

This kind of got us thinking and we dug around the Microsoft support site for examples of effective [email attachment] size limits. Of the two examples found (shown below), I think what is glaringly obvious is that a 10MB limit as suggested by the reseller is, if anything, on the generous side.

Examples of effective size limits

Example 1
• The global setting is set to 5 MB.
• The Exchange SMTP connector is set to 3 MB.
• The SMTP virtual server is set to 4 MB.
• The user mailbox setting is set to 2 MB.

Example 2
• The global setting is set to 2 MB.
• The Exchange 2000 SMTP connector is set to 5 MB.
• The SMTP virtual server is set to 2 MB.
• The user mailbox setting is set to 3 MB.

I then looked at my own folders full of PowerPoint presentations. I am - after all - Accellion's "marketing guy," and 20MB sized files are dime a dozen.

So, here is a question with an obvious answer. Why fight a battle on controlling email attachment size limits that nobody has a clear solution for when you can use the field-proven Accellion Courier File Transfer Appliance that would seamlessly integrate into your Microsoft Exchange/Outlook and give users the ability to send really large files without overwhelming the messaging infrastructure?

Granted, the CEO may not notice the change. But, as the saying goes, "no news is good news" as far as limiting email attachment sizes and allowing daily business processes are concerned.

Or, as I like to think, you should have the "email + unlimited large attachment size" cake and eat it too.


Click here to request more info on Accellion Courier SFTA

1 comment:

Anonymous said...

Microsoft Exchange Team blog says that "Microsoft has a best practice of a 10MB limit. Exchange Server 2003 by default sets the global message size limit to 10MB"