I have always found it frustrating that when using two computers, eM client would only show me sent messages from the computer being used (not syncing with the root gmail account). After tooling around in the platform, I found a very simple fix that is likely just an out-dated setup -
Go into Tools / Accounts / IMAP / Special Folders - Uncheck the box and switch “Sent Mail” to “Sent”. The former won’t recognize Gmail’s sent folder because the URL is actually listed as “Sent”.
Once updated, your eM client will sync with Gmail and show ALL messages sent, not just those from that particular installation of eM client.
I am sure there is a post buried somewhere with this solution, but I couldn’t easily find it so I figured I’d go ahead and post anyway.