Dropbox Sign can be used in two different ways with Mail2Sign. One way is sending email attachments (documents) with embedded Dropbox Sign tags.

The following video is a demonstration of how this works...

With Dropbox Sign tags, you can set the position of signatures, initials, dates, and other fields.

Each tag indicates which signer it is assigned to. With mail2sign, signers are assigned in their order. For example, a document sent in an email addressed as:

would assign Alex Right to signer1 and Bill Jones as signer2, respectively.

Example document with embedded text tags. Note text tags should be made the color of the page - be invisible. They are red in the above image just for clarity.

With the above document, Dropbox Sign will automatically create signature and initial fields, as in the example below...

Here are some tag examples:

[sig|reg|signer1] < a signature field, required and for the first recipient
[sig|reg|signer0] < a signature field, required and for the sender
[date|req|signer2] < a signature field, second recipient
[text|noreq|signer1] < a text field, not required, for the first recipient
[initial|req|signer3] < an initial field, required, for the third recipient

More about Dropbox Sign text fields can be found here: https://developers.hellosign.com/docs/text-tags/walkthrough/

and in this article in the context of Salesforce (and Mail2Sign).

FAQ

What if you send two recipients an email with a document that only has text tags for one signer?

The recipient without a matching text tag will be added as a document copy recipient.

What if you send an email to only one recipient, and the document has tags for two signers?

You will receive an error notification that there were not enough recipients for the document sent.

What if you send a document without any Dropbox Sign tags?

The recipients on the "To" line of the email will receive the document. Dropbox Sign will append a "signature page" to the bottom of the document where recipients will sign.