Below are demo sites generously made available for trial use by various members of the SquirrelMail community. Please be courteous when using any of these systems. Listing is in alphabetical order.
ACME Anvils SquirrelMail Demo
http://example.org/webmail/demo (this is just an example/placeholder and is not an actual, real demo site)
Email.Uoa.Gr SquirrelMail Demo