To see mail sent using Baya V3 in the Sent Items folder, you will have to enable the Save to Sent Items for the user using the Admin Panel.

To enable the Save to sent items option for your domain,

1. Log in to the Admin Panel with valid credentials.
2. On the left pane, click the Domain name
3. Select the Mail settings
4. Enable the Save to Sent Items

To enable the Save to sent items option for a user,

1. Log in to the Admin Panel with valid credentials.
2. On the left pane, click Users
3. On the details pane, select the Mail settings
4. Enable the Save to Sent Items

https://skyconnect.mithi.com/faqs/faqs-baya-v3/how-to-enable-the-save-to-sent-items-option-for-your-domain/#comment-20


To enable the Save to sent items option for a user,
Using CSV.

Sample CSV format :
save2sent.csv
username,classofservice,enablesave2sentitems
testuser,,yes

Below can be the possibilities if the sent items are not getting saved in Sent Items folder.
1] Save to Sent option is disabled at Domain/COS/user level.
2] User quota is full