Hi, I just received an email from LE that looks like this:
Action is required to prevent your Let’s Encrypt certificate renewals from breaking.
Your Let’s Encrypt client used ACME TLS-SNI-01 domain validation to issue a certificate in the past 60 days.
TLS-SNI-01 validation is reaching end-of-life and will stop working on February 13th, 2019.
You need to update your ACME client to use an alternative validation method (HTTP-01, DNS-01 or TLS-ALPN-01) before this date or your certificate renewals will break and existing certificates will start to expire.
If you need help updating your ACME client, please open a new topic in the Help category of the Let’s Encrypt community forum:
Please answer all of the questions in the topic template so we can help you.
For more information about the TLS-SNI-01 end-of-life please see our API announcement:
Let’s Encrypt Staff
The problem is that I manage quite a few servers and it would be very helpful if the email also provided the domain name that was tried, so that I can know which client needs to be upgraded.