All your certificates are automatically renews using LetsEncrypt. As an administrator, you can also see ther status in the command cert-status:
Domain | Valid from | Valid until | Days left | Issuer | Full domains list | Type | DANE | Status | Details
smtp | 07/02/24 | 07/05/24 | 43 [==== ] | R3 | DNS:smtp.homebox.space | RSA | OK | Live | OK
openpgpkey | 07/02/24 | 07/05/24 | 43 [==== ] | R3 | DNS:openpgpkey.homebox.space | EC | | Live | OK
* | 10/02/24 | 10/05/24 | 46 [===== ] | R3 | DNS:*.homebox.space | EC | | Live | OK
| 10/02/24 | 10/05/24 | 46 [===== ] | R3 | DNS:homebox.space | EC | | Live | OK
pop3 | 10/02/24 | 10/05/24 | 46 [===== ] | R3 | DNS:pop3.homebox.space | EC | OK | Live | OK
pubsub | 10/02/24 | 10/05/24 | 46 [===== ] | R3 | DNS:pubsub.homebox.space | EC | | Live | OK
prometheus | 10/02/24 | 10/05/24 | 46 [===== ] | R3 | DNS:prometheus.homebox.space | EC | | Live | OK
autodiscover | 11/02/24 | 11/05/24 | 48 [===== ] | R3 | DNS:autodiscover.homebox.space | EC | | Live | OK
main | 12/02/24 | 12/05/24 | 49 [===== ] | R3 | DNS:main.homebox.space | EC | | Unknown | OK
autoconfig | 12/02/24 | 12/05/24 | 49 [===== ] | R3 | DNS:autoconfig.homebox.space | EC | | Live | OK
rspamd | 25/02/24 | 25/05/24 | 62 [======= ] | R3 | DNS:rspamd.homebox.space | EC | | Live | OK
mta-sts | 25/02/24 | 25/05/24 | 62 [======= ] | R3 | DNS:mta-sts.homebox.space | EC | | Live | OK
ldap | 25/02/24 | 25/05/24 | 62 [======= ] | R3 | DNS:ldap.homebox.space | EC | | Live | OK
conference | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:conference.homebox.space | EC | | Live | OK
proxy | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:proxy.homebox.space | EC | | Live | OK
xmpp | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:xmpp.homebox.space | EC | Error | Live | OK
upload | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:upload.homebox.space | EC | | Live | OK
files | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:files.homebox.space | EC | | Pending | OK
sogo | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:sogo.homebox.space | EC | OK | Live | OK
vjud | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:vjud.homebox.space | EC | | Live | OK
www | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:www.homebox.space | EC | OK | Live | OK
imap | 26/02/24 | 26/05/24 | 62 [======= ] | R3 | DNS:imap.homebox.space | EC | OK | Live | OK
webdav | 23/03/24 | 21/06/24 | 89 [==========] | R3 | DNS:webdav.homebox.space | EC | OK | Live | OK
If anything does not work, you will receive an email from LetsEncrypt, that will tell you your certificates have not bee renewed, before they expires, giving you enough time to investigate:
Hello, Your certificate (or certificates) for the names listed below will expire in 19 days (on 2024-02-24). Please make sure to renew your certificate before then, or visitors to your web site will encounter errors. We recommend renewing certificates automatically when they have a third of their total lifetime left. For Let's Encrypt's current 90-day certificates, that means renewing 30 days before expiration. See https://letsencrypt.org/docs/integration-guide/ for details. imap.homebox.space pop3.homebox.space smtp.homebox.space For details about when we send these emails, please visit: https://letsencrypt.org/docs/expiration-emails/ In particular, note that this reminder email is still sent if you've obtained a slightly different certificate by adding or removing names. If you've replaced this certificate with a newer one that covers more or fewer names than the list above, you may be able to ignore this message. For any questions or support, please visit: https://community.letsencrypt.org/ Unfortunately, we can't provide support by email. To learn more about the latest technical and organizational updates from Let's Encrypt, sign up for our newsletter: https://letsencrypt.org/opt-in/ If you are receiving this email in error, unsubscribe at: http://delivery.letsencrypt.org/track/unsub.php*** Please note that this would also unsubscribe you from other Let's Encrypt service notices, including expiration reminders for any other certificates. Regards, The Let's Encrypt Team