Send email inviting existing participants to sign at any given time
<p>I am generating an envelope with multiple signers.  When the envelope is created, all signers are set to in-person.  Later, the signers may change to email signers.  </p>

<p>When the signers are changed to email signers, I would like to not email them.  I would instead prefer to email them at any time after they are changed to email signers (eg when an admin in my app presses an "email now" button).</p>

<p>Is this possible?  I have not been able to track down when and how emails are sent notifying email signers that a document is available for them to sign.</p>