Why can’t I send/receive large attachments over e-mail?

February 22, 2012
It’s a fair question! In a day when Internet connections are so fast and hard drive space so cheap, it’s fair to ask why you can’t send 50MB attachments over e-mail.

Technically, there’s nothing standing in our way. You’ll find directions all over the Internet explaining how to raise or completely remove the e-mail message size limit in Microsoft Exchange – your e-mail server. So why doesn’t your network administrator (that’s me) let you send massive attachments? The customer’s always right, right?

Bombs away!

Imagine that UPS shows up at your door with a package. It looks like a reasonable size, so you put it in one hand, sign for it with the other, then take it inside. But that’s not how e-mail is received.

When someone sends you an e-mail, your front door is already open and don’t have the opportunity to see how big the package is until the entire thing is in your living room!

So, say you’ve successfully lobbied your IT guy to completely remove all incoming e-mail size limits. Then, a few weeks later, you let an employee go. You didn’t know it, but she knows more about computers than she let on and she wants you to feel her pain. Knowing that your mail server has to receive any message that is sent to it, she sends a 50MB PDF to a mailbox that is infrequently checked, like “info@myformerworkplace.org” 50 times. What has she accomplished?

1. Your Internet connection came to a crawl for three hours.
2. Your mail server has just spent the better part of three hours downloading 2.5GB of e-mail slowing down the sending and receiving of everyone else’s good mail.
3. Your e-mail database could now be perilously close to its size limit. When this happens, all mail services stop. Did you know that all of the mail for everyone at your company lives in one, massive file? Better keep an eye on its size!
4. The overall storage capacity of the drive that your mail lives on could be very low which will also cause mail services to stop if not cause the entire server to stop responding.

If a 25 MB attachment falls in a forest, does it make a sound?

“OK, fine. Fair enough. We have to draw the line somewhere. How about 25 MB?”

25 MB sounds reasonable. A PDF of hundred pages and some images could be around that size. An instruction manual, perhaps. So, you ask your IT guy to institute a 25 MB limit, then you send this instruction manual to a colleague at another company, but it gets returned to you.

Why did it get returned if you’re allowed to send it? Because although you’re allowed to send 25 MB attachments, 99% of the Internet adheres to the worldwide inbound limit of 10 MB e-mail messages. So although you can send it, no one can receive it. Who attempted the offense? The would-be home invader thwarted by a locked door, or the homeowner who protected his home? (It’s the former.)

But, but…Gmail lets me!

Ah, yes. Gmail, Hotmail, Yahoo and the rest of the freemail crowd. They allow you to send attachments up to 25 MB, but the same rule applies – you can send but it won’t be received.

“But they let me receive 25 MB attachments, too.”

Yes, they do but only so they don’t have to field questions like, “Why can’t I receive large attachments?” Answering questions takes people, and people get paid for answering questions, but their services are free, therefore no people, therefore no questions, etc.

And, free, as they say, isn’t free. You’re still paying for Gmail by being shown ads which are generated by mining your e-mail for personal information. That advertising revenue lets them provide an immeasurable amount of storage so they don’t have to answer questions, which they can’t because it’s free, blah, blah, blah…

I’m not listening. I want to get higher attachment size limits and more storage capacity

Wow, you’re really not listening, are you? The attachment limit isn’t the problem, it’s the solution!
A few weeks ago, a client of mine experienced the worst of this problem. They were sent an invitation to bid on some work, but the attachment that the architect sent them was over the 10 MB limit. My client didn’t get the attachment and didn’t get the work. Should I have raised the limit on inbound e-mail? Possibly, but how high? What if I raised it to 25 MB and the same e-mail had a 26MB attachment instead?

To mitigate this problem, I had previously configured their spam filtering service to return the offending e-mail with a message letting sender know that her e-mail was rejected due to its size. I presume the sender saw the warning, was too confused or embarrassed by it and promptly ignored it.

What’s the lesson here? The lesson is not that my client’s network isn’t well managed, but that the sender’s network isn’t! It was highly irresponsible for the network administrator of the architecture firm to let that message leave their mail system. Had the architect’s IT person stood his/her ground on the outbound limit, the message never would have left their mail system which would have forced the sender to compress the file, or upload it to a file sharing site. Either way, 100% of the recipients would have received the architect’s attachment. We do the same thing in real life – if we want to send a package, we don’t stick a stamp on it and set it out with the rest of the mail. We take it to a file sharing site – UPS – and have them ship it for us.

Final thoughts

There may come a time that the 10 MB limit obsolesces and 25 MB becomes the new limit. When that time comes, I’ll be the first to change our clients’ inbound and outbound limits. But as long as the out-of-the-box Exchange limit is 10 MB, or the prevailing wisdom of the Exchange administrator community changes, it’s still 10 MB. It’s the law!