Letencrypt Auto renew and dovecot problem

I've enable auto renew for Letencrypt SSL , it can renew SSL cert every 90 days .
But yesterday I find that , my iPhone non-stop pop up said that SSL cert expired.
Once I restart devecot service manually , problem solved.

Is that a solution for trigger auto restart devecot service once renew the letencrypt SSL cert ?

Thanks
Kevin Lo

Hello The restart of the service should be automatic

I'm also having this issue, but with the web server (Nginx&Apache profile). When a domain's Letsencrypt SSL gets renewed, browser keeps showing expired certificate. I have to manually reload or restart the webserver before the renewed cert starts working.