Amcrest Forum

Almost the same solution:

1. Get a wired connection
2. Login with wired ip address
3. set SMTP settings
4. Test smtp (this should work)
5. Remove the cable
Optional:
6. Login with the wireless ip addres
7. Test smtp (this should still work)

I struggled with this for gmail, it turns out, the recipient needs to be filled-in and submitted, so it goes into the box below where entered, and then save it.

You probably need to enable "less secure apps" for gmail, so Amcrest can use your gmail smtp.

If you have 2-step verification enabled, you'll need to generate an app password to use.