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One of the features I am working on for my app (https://bigpicture.site) is the ability for each customer to have a custom subdomain in their url (similar to slack where each workspace is in the form of {name}.slack.com.)

I understand the technical details of setting up the wildcard subdomains and handling it, but I am curious if there is a canonical list somewhere of subdomains I shouldn't let a customer register.

For instance, I wouldn't want a customer to use www as their workspace name. www.bigpicture.site should be reserved.

What other subdomain names should be reserved? Just from brain storming, here is the list I came up with. But I'd love to know if there is a better list somewhere:

www mail ftp web smtp imap pop pop3 blog support about social billing admin knowledge help community

Additionally, I am going to reserve anything that starts with the letters "bp" so I can use those internally.