Let’s Encrypt からのメール．
Let’s Encrypt certificate expiration notice for domain “itl.mydns.jp” (and 1 more)
Hello,
Your certificate (or certificates) for the names listed below will expire in 20 days (on 11 Aug 18 06:35 +0000). Please make sure to renew your certificate before then, or visitors to your website 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.
itl.mydns.jp
mish.myds.me
For any questions or support, please visit https://community.letsencrypt.org/. Unfortunately, we can’t provide support by email.
Regards,
The Let’s Encrypt Team

どうも Synology NAS に，最初に登録したものに対して期限が迫っているということみたい．
Synology NAS の DSM は自動で更新してくれるそうなので，このまま様子見．

2018/08/01 再度，Lets’ Encrypt から．
Hello,
Your certificate (or certificates) for the names listed below will expire in 9 days (on 11 Aug 18 06:35 +0000). Please make sure to renew your certificate before then, or visitors to your website 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.
itl.mydns.jp
mish.myds.me
For any questions or support, please visit https://community.letsencrypt.org/. Unfortunately, we can’t provide support by email.
If you are receiving this email in error, unsubscribe at http://mandrillapp.com/track/unsub.php?u=30850198&id=547c6b491faf4f03b0ecc8cb3871a0b2.RsjpgIgXcXbPKK4%2Fg4vK9vppkUw%3D&r=https%3A%2F%2Fmandrillapp.com%2Funsub%3Fmd_email%3Diwao.n%2540ae.auone-net.jp
Regards,
The Let’s Encrypt Team