This option will send images to Teleport only when motion is detected. Dahua firmware does not seem to support scheduled recurring interval SMTP or Http image upload, though this may vary depending on the camera model. Ftp based upload does support both recurring and event based image upload.
While the exact interface may vary depending on the camera firmware version, here are the steps to setup SMTP/email on the latest firmware of newer Dahua cameras.
Browse to the Email configuration on the camera. This is done by logging into the camera firmware web page once you know it's IP address. For example : http://192.168.0.93 To discover the cameras IP address you can look at devices connected to your router or use Dahua Config Tool
Then go to Network Settings -> Email
Enter mail.teleport.io as the server, 2525 as the port, feed ID as username, and password provided on the feed dashboard 'Live image' tab. Use feed@devmail.teleport.io as both the sender and receiver emails. Make sure Attachment is checked. Do not use Health Mail as it does not send an image. Apply changes and click Test to test the connection. Note the test itself will not show the image on the Teleport feed.
One more step is required to have the camera upload images. It needs a schedule or some sort of triggering event. In the Event -> Video Detection section make sure Send email is added as a Event linkage, check Enable and click Apply. Images should now upload when motion is detected.