Impossible to add mail sending (SMTP server) functionality to an account post-facto
When initially configuring/adding an account, in the wizard, it is possible to specify "None" as the SMTP/sending server type, which creates an account that is receive-only. However, if you later change your mind, you cannot retroactively mail sending capabilities in the email account in Evolution's preferences.
Ideally, we should be able to add/disable/enable both the receiving and the sending of an email account, independently, at any time; at least, that's what I've seen most other email clients (including Thunderbird) allow. Recreating the account from scratch everytime would be inconvenient because there might be a lot of things set up around it (including email filters, signatures, etc.).
Tested with Evolution 3.48.4 on Fedora 38, but this affected every previous version I've seen.