Logic for iRule on a single VIP to redirect http (80)traffic based upon uri.

When HTTP_Request { 
    if  { [HTTP::Host] contains "webmail.com" } { 
        HTTP::respond 302 Location "https://outlook.office365.com/owa/sample.net"
    } elseif { [HTTP::Host] contains "webmail.sample.com" } { 
        HTTP::respond 302 Location "https://outlook.office365.com/owa/sample.net"
    } elseif { [HTTP::Host] contains "onedrive.com" } { 
        HTTP::respond 302 Location "https://login.microsoftonline.com/login.srf?"
    } else {
        reject
    }
}

Or you can preferably use a switch command :

When HTTP_Request { 
    switch -glob [HTTP::host] {
        "webmail.com*" -
        "webmail.sample.com" {
            HTTP::respond 302 Location "https://outlook.office365.com/owa/sample.net"
        }
        "onedrive.com*" {
            HTTP::respond 302 Location "https://login.microsoftonline.com/login.srf?"
        }
        default { reject }
    }
}