Incident communication.
THE FIRST MESSAGE
Sent as soon as you know, before you have the answer.
"I am aware the site is down. I am investigating and will update you within thirty minutes."
That buys you time and prevents the client wondering.
THE UPDATE
Even with nothing new. "Still working on it, next update in an hour."
Silence is what turns an outage into a lost client.
WHEN IT IS A SERVER PROBLEM
"The server is affected. The provider is working on it. I will update you as soon as I know more."
Accurate, and it positions you as managing the situation rather than helpless.
WHEN IT IS RESOLVED
What happened, briefly. What was affected. What was done.
Whether anything was lost.
WHEN IT WAS THEIR CHANGE
Fix it first. Then explain factually, without blame, and suggest backing up before future changes.
WHAT NOT TO WRITE
Technical detail nobody asked for Excessive apology, which suggests greater fault than existed Blame directed at anyone
THE AFTER-ACTION NOTE
A short account, sent afterwards. Clients value being told, and most providers do not.