Not all mail servers automatically save sent mail. Gmail does, but many don't.
Hence if SMTP configuration is switched on, outgoing mail is not saved in sent mail. This is an issue as we want outgoing mail, e.g., invoices, saved.
The solution is for Kashflow to implement IMAP APPEND functionality within SMTP configuration settings.
This would allow a user to select that they want mail saved and to what folder, default "Sent".