So, here's the first thing that I handle today...
(Our chat module dings. I go forth and answer it):
the subject line of the chat is, "Hi, I've emailed you a word doc file earlier on, for a quote but I did not include a couple of pages."
Me: Hi, FRED (Fred is a psuedonym, to protect the not-so-innocent), It's extremely unlikely that a few pages will affect your quote, but if you're concerned, you can send me the revised file.
Fred: Hi, Hitch, would you mind to email me back the word doc so I can revise it
Me: 
What? There's no reason for me to send it back to you, it's already still on your computer. Just make the changes you want to make, and re-send it.
Fred: I can't find that version.
Me: When you attach or send a file, you're only sending a copy. You don't actually send us your only original. So I can--
Fred: I've done many changes.
Me. (sighing): When did you send this file to us?
Fred: A couple hours ago.
Me: Okay, well, you can probably download it from your OWN email, because it will be there in the attachments. But if you think you need me to send this file back to you, the one you sent four hours ago, I'll do that. (At this point, I start thinking about suicide, as an honorable way out of this profession.)
Fred: I've used the online form. (Our online email form).
I would like that version if possible.
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Yes, folks, you too can be a highly-paid bookmaker.
Hitch