Re: EMAIL Syntax Validation

["Glenn Gundermann" <ggundermann@xxxxxx>]

Thanks Scott!!

Glenn :D

> Hi Glenn,
>
>  > I can't find it.  :-(
>  >
>  >> Scott Klement wrote an email validater called VALMAIL. A
>  >> search through the archives should provide a link to it.
>
> This is a somewhat tricky question because there are very few rules
> involved in the syntax of an e-mail address.  Basically, anything can
> precede the '@' symbol, as long as it's properly quoted, and is allowed
> by the destination e-mail server.  The part after the @ symbol must be a
> valid TCP/IP domain name.  So that's not a lot of validation!
>
> My first approach to the problem was to check the syntax (Again, that
> doesn't provide much help, since the syntax is so broad) and then do a
> DNS lookup on the domain name portion.   That way, you know that it's a
> valid domain name that's available on the Internet.
>
> That code was called VALMAIL (it's the one Matt mentioned) and is
> available to System iNetwork members (a free, "Associate" membership is
> all you need) at the following link:
> http://www.iseriesnetwork.com/article.cfm?id=17633
>
> As I recall, there's an issue with the GetMX routine in that service
> program, but it only surfaces with some DNS servers.  The solution (to
> make it work everywhere) is to add a '.' to the end of the domain
> name... it should be as easy as changing this line of code:
>
> c      eval      count = GetMX(dom: MXSIZE: mx: pty)
>
> to this:
> c      eval      count = GetMX(dom+'.': MXSIZE: mx: pty)
>
> The problem with that method is that it has to do a DNS lookup on every
> e-mail address you enter...  That can be slow (depending on how fast the
> addresses are entered) and it also can produce "false failures" if your
> Internet connection happens to be down, or if the company who owns the
> e-mail address has their DNS servers down for maintenance or something,
> it'll come up as a "bad address".
>
> The other common method is to check the basic syntax using a regular
> expression.  Here's an article I wrote (also requires a free,
> "associate" subscription to SystemiNetwork.com) that demonstrates that
> technique from RPG:
> http://www.systeminetwork.com/article.cfm?id=52826
>
> The regular expression method only checks the syntax (no DNS lookup) but
> is stricter.  Theoretically, it can reject a valid e-mail address --
> though, most of the invalid ones that would fail the test are so obscure
> that it doesn't make much difference.
>
> Good luck