一个判断email合法性的函数[非正则]

<%
function isvalidemail(email)
dim names, name, i, c
isvalidemail = true
names = split(email, "@")
if ubound(names) <> 1 then
isvalidemail = false
exit function
end if
for each name in names
if len(name) <= 0 then
isvalidemail = false
exit function
end if
for i = 1 to len(name)
c = lcase(mid(name, i, 1))
if instr("abcdefghijklmnopqrstuvwxyz_-.", c) <= 0 and not isnumeric(c) then
isvalidemail = false
exit function
end if
next
if left(name, 1) = "." or right(name, 1) = "." then
isvalidemail = false
exit function
end if
next
if instr(names(1), ".") <= 0 then
isvalidemail = false
exit function
end if
i = len(names(1)) - instrrev(names(1), ".")
if i <> 2 and i <> 3 then
isvalidemail = false
exit function
end if
if instr(email, "..") > 0 then
isvalidemail = false
end if
end function
%>