How it works
When you add an Exchange account, Outlook takes the domain from your email address and looks for an Autodiscover
service for it — typically at autodiscover.yourcompany.co.uk, which your DNS points at your email provider.
The service replies with everything Outlook needs: server names, connection methods, and where your mailbox lives.
Phones do much the same for ActiveSync.
The DNS side is usually a CNAME record called autodiscover pointing at your provider, or an SRV record
named _autodiscover._tcp. Your provider tells you which to use.
What breaks it
- A leftover record from a previous provider after a migration — the classic cause of endless password prompts.
- Your website answering instead. Outlook can try
yourcompany.co.uk/autodiscover/…; if your web host answers with something unexpected, Outlook gets confused. - Certificate problems on the Autodiscover address, which cause security warnings.
- Records that were never created, so automatic setup fails and someone types server settings by hand.
How to test it
In classic Outlook, hold Ctrl, right-click the Outlook icon in the system tray and choose Test Email AutoConfiguration. From outside your network, Microsoft’s free Remote Connectivity Analyzer at testconnectivity.microsoft.com runs the same tests. If you are seeing repeated password prompts, our guide on why Outlook keeps asking for your password goes through the fixes.