Thanks for a bug report. You can use either SMTP or Sendmail, or you can fill garbage in the SMTP server address, to avoid accidental sending (a single letter 'a' worked here just fine).

There is a very old request to support None type for sending too, I only do not have its number handy. Andre, any luck with that, please?

I'm only aware of bug 235022 and bug 664030 so I don't think it's a dup.

Thanks Andre, then I'll use this bug report.

I also added a helper function to evolution-data-server, e_util_identity_can_send(), which checks whether the identity source has configured also its transport source and this is not "none".

In the evolution part, I let it disallow to create an account with both sending and receiving parts being "none", such accounts are useless. I did also some other changes in the account editor, like the Receiving Email and Sending Email tabs are shown only is their respective backend is not "none". It makes sense, because the type of the respective part cannot be changed for existing accounts.

I also made the Edit->Preferences->Mail Accounts smart enough to show the sending part backend name in the Type column when the receiving part backend is "none".

Created commit_2c8fdea in eds master (3.25.4+) [1]
Created commit 06475e4 in evo master (3.25.4+)

[1] https://git.gnome.org/browse/evolution-data-server/commit/?id=2c8fdea