default CRM email sent as recipient, not user #2480

Describe the bug
A clear and concise description of what the bug is.

In the Frappe CRM module, replying to an email has no default email user. If not explicitly chosen in the to field droplist, the email is sent from the RECIPIENT email address which is obviously not valid. A from header is added with the email address of the recipient (copy of to header), which is rejected (rightly so) by the SMTP server.

To Reproduce
Steps to reproduce the behavior:

1. Go to a lead or deal or whatever
2. view emails
3. Click on reply
4. Compose and email
5. Send email - sender copies frappe user name and RECIPIENT email address.
   Expected behavior
   A clear and concise description of what you expected to happen.

The default sender should match the sender from the prior address or current Frappe CRM user.

Note- when clicking "new email" the sender address is pre-populated with the default (and can be changed via the droplist). I would expect that when hitting reply, the behavior would be the same as above- the current user email would be selected, rather than nothing.

In no case would I expect the recipient's email address be used as the sender, even if the current user doesn't have a valid email address set up in Frappe. In that case, it should fail.

Screenshots
If applicable, add screenshots to help explain your problem.
Not applicable, as would expose confidential client/user information (email addresses) - can provide to a developer privately if requested. This appears in the the UI and in the Frappe logs.

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

MacOS/Safari
Frappe Framework: v16.20.0
ERPNext: v16.21.1
Wiki: v2.0.0
Frappe Builder: v1.0.0-dev
Print Designer: v1.6.7
Frappe CRM: v1.73.0