Add support for account without outgoing SMTP server

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

6.714

Problem you are trying to solve

Now that I didn't do any code contributions for K-9 for quite a while, I just switched from an old debug version to the official beta version on Google Play. So far, the new account setup looks quite nice. I'm sure it will help many new users. However, I noticed a few problems that I will be creating issues now.

I have an email account that apparently does not support sending mail via SMTP (office356, smtpclientauthentication is disabled for the tenant). I would still love to add that account to K-9, simply without an SMTP configuration. In the old account setup, I could just skip the outgoing server and add an account that is receive-only. This no longer works with the new account setup.

Suggested solution

Add a way to skip adding the SMTP server

Screenshots / Drawings / Technical details

No response

Start by tracing the new account setup flow and the outgoing SMTP configuration step in the Android app. Confirm how the setup handles accounts without an SMTP server, then verify that a receive-only account can be added successfully while normal sending accounts remain supported.