Email is probably one of the very best ways to document everything that's happening during a transaction. It gives you the ability, without extra effort, to document precisely when you sent notice to a client about any facet of the transaction. If you're delivering a document via an email attachment, you at least have the ability to show when it went out. There are services that will also track it, sending you a notice when the email is opened, as well as when they open the attachment.
There's also the very positive bonus of being able to verify events or clarify questions on an almost immediate basis. If you're not clear about a client's intentions in a situation, sending a quick email can get you the answer. And, that's not even mentioning the value of their email reply, which saved to a file will be there if you ever need to prove that they said what they did.
What about multiple buyers or sellers in different locations? It's now immediate and verifiable that you sent the exact same information to all involved. And, getting their responses back via email gives you that all-important verification file copy of what each said. If there is a variant response from one individual, you can forward it to the others to get their take, as well as generate discussion on their end to resolve the issue.
If you're not emailing yourself with notes, you're missing the boat on the best documentation and self-reminder mechanism available. I use Gmail, with frequent emails to myself to document a situation, or just to remind me of why I made a decision or took a certain action. They are filed away permanently, with the great ability to use Google search inside my email to locate the items later. Using the voice-to-text services of Jott.com, I can do this with my cell phone and never touch a keyboard.
Look into how to better use email in your business for accuracy, documentation, and just a very discoverable record of what has happened in a transaction.

