Please help us help you and fill where relevant:
Your LimeSurvey version: 6.2]
Own server or LimeSurvey hosting: self-hosted
Survey theme/template: fruity
==================
In the mail setting, there is the send test mail button, press the button, a pop-up widow show the email it will send to. I press the comfirm, but nothing happen, I have no new email in my inbox.

I check the spam and the email setting, it's correct.

But I can send the participant email normally, what the problem could be?