I want to set an account for incoming only, But there is no wayt to do this--no smpt option for no address.

In tools menu (Alt+T) > account setting the outgoing server (SMTP) are set up at the bottom of the list. check there that you have at least one.

Delete any associated with the account you do not want to send.

In the account name in the list (above server settings) check that both account have the remaining SMTP server selected.

This means pressing reply or whatever wil use your default outgoing server for both.

Thanks. I'll try to be clearer. I click on an email address in another app. Of I use the sendmail vbasic function. It tells Tbird to setup an outgoing email. I have 2 email accounts defined. Tbird will choose one of the 2 arbitrarily. But one of those 2 I only want to use for incoming. How do I mark it? If I delete the outgoing smpt for the incoming only account, it will still use that account name, but with the smpt server for the other account.

If Thunderbird is close the default in the SMTP server list will be used. If Thunderbird is open an a mail account is selected it will be used.

Yes, but how do I tell it must not choose one of the accounts which I only use for incoming?

perhaps this add-on? https://addons.mozilla.org/En-uS/thunderbird/addon/correct-identity/?src=ss