My mastodon server cannot send new user confirmation email

When a user registers, the webpage will show ‘’Confirmation email sent’, but when I check my email (including spam emails), there is no confirmation email in it.
The strange thing is that in the interactive wizard for installing mastodon, the smtp information I filled in can run successfully and send out a test email. I use zoho’s smtp service. There is also only the initial test email in the outbox of this email, and all the user registration confirmation emails are not sent.
How can I troubleshoot and solve this problem?

My smtp information:

SMTP_SERVER=smtp.zoho.com
SMTP_PORT=587
SMTP_LOGIN=godmeng@xxxxxx.one
SMTP_PASSWORD=xxxxxxx
SMTP_AUTH_METHOD=plain
SMTP_OPENSSL_VERIFY_MODE=none
SMTP_FROM_ADDRESS=godmeng@xxxxx.one

It works except sending confirmation email

Can you post a whole exception from the sidekiq log - it apparently crashes … Also please post as text (use ```` to display the log as-is without any formatting).