Question

I’m building a web email client and I’m interested in easy ways to figure out imap or pop3 emails. Is there a tool to help figure this out?

I’m assuming if not, my best bet would be

try { imap.domain.com } 
catch{ 
        try { mail.domain.com } 
        catch { ...etc ... }
} 

Answer 1

There is no way. Your best bet is to try the domain of the e-mail, plus the usual prefixes, as you suggest. Even then, an IMAP server may be running in a non-standard port; then you have no way of knowing.