Some users find that mail does not go out, and it appears that SMTP is missing, even though the Settings page looks correct. It has been reported that this is cured by opening akonadiconsole and adding Mail Dispatcher Agent.

If the computer was suddenly turned off in suspend mode (e.g. by a power cut) sometimes e-mails simply stay in the outbox without being sent, but no error message is generated either. This may be due to the fact that the Mail Dispatcher Agent is set to “offline” in the configuration file during suspend and is not changed back due to the crash. Edit the following file:

~/.config/akonadi/agent_config_akonadi_maildispatcher_agent

and change

[Agent]
Online=false

to

[Agent]
Online=true