What problems can @ in URLs cause?

[eluser]newsun[/eluser]
Subject pretty much says it. Need to be able to use emails addresses in URLs, so what issues can this cause by allowing the @ character?

[eluser]xwero[/eluser]
Not that i know but i think the EL developers kept the allowed characters setting so specific to guide the users of the framework to make as easy as possible urls. But nothing should stop you form adding the characters you need in the urls.

[eluser]simonmaddox[/eluser]
I'd imagine it's to do with how some browsers might handle FTP connections. To connect to an FTP site in your browser, you'd do:

ftp://user:pass@site (or ftp://user@site)

If you type the following URL into the address bar, certain browsers (might) interpret it as an FTP site:
yoursite.com/email/[email protected]

Is that a user called "yoursite.com/email/my", or a http request?

Pure speculation on my part, by the way.

[eluser]xwero[/eluser]
simonmaddox that is if you put the @ in the domain part of the url but i guess newsun wants to put the email in one of the segments of the url.

[eluser]simonmaddox[/eluser]
Are you 100% sure that's the case for every browser out there? Even the obscure ones, and mobile browsers?

As I say, pure speculation on my part, but I don't think we'll get a specific reason for why this is in the disallowed character list until someone at EllisLabs replies.

EDIT: Why not urlencode the @ symbol? It'll go into the URL as % 40 that way.