nanog mailing list archives
Re: Programmers with network engineering skills
From: Joe Greco <jgreco () ns sol net>
Date: Mon, 12 Mar 2012 20:31:21 -0500 (CDT)
Owen DeLong wrote:http://en.wikipedia.org/wiki/Email_address#Valid_email_addresses You may have noticed my particular test wouldn't accept foo!bar!ucbvax!user format addresses, either. It works well enough for my purposes. I did not claim it was perfect.Why not leave it to the MTA to decide what is a valid address? It only requires a few SMTP commands to the MTA to know if it will accept it. Normally the MTA will tell you after the "rcpt to:" command if it will accept it (i'm ignoring some badly behaving MTAs who will swallow anything and then bounce, no point trying to work around such crap). No need to re-invent the wheel, unless you're actually creating an MTA or something similar. Who is to say that even IF your address verifier verifies it as valid that the MTA is configured to allow it (or the other way around)? MTAs can be arbitrarily configured to (dis)allow "bang path" addresses, IP addresses etc.
The ideal world contains a mix of techniques. You cannot just blindly leave it to the MTA to decide what's valid. Along that path lies madness. How do you pass the address to the MTA? Don't do it as a system() call unless you want someone to own your box with a semicolon. Do you allow \n? \r? Do you allow \\? There is a certain amount of paranoia that is prudent, and a certain amount that is actually necessary... though it's true that implementations often don't bother to work that out correctly... ... JG -- Joe Greco - sol.net Network Services - Milwaukee, WI - http://www.sol.net "We call it the 'one bite at the apple' rule. Give me one chance [and] then I won't contact you again." - Direct Marketing Ass'n position on e-mail spam(CNN) With 24 million small businesses in the US alone, that's way too many apples.
Current thread:
- Re: Programmers with network engineering skills, (continued)
- Re: Programmers with network engineering skills William Herrin (Mar 08)
- Re: Programmers with network engineering skills Carlos Martinez-Cagnazzo (Mar 12)
- Re: Programmers with network engineering skills Tei (Mar 12)
- Re: Programmers with network engineering skills Keegan Holley (Mar 12)
- Re: Programmers with network engineering skills Owen DeLong (Mar 12)
- Re: Programmers with network engineering skills Michael Thomas (Mar 12)
- Re: Programmers with network engineering skills William Herrin (Mar 12)
- Re: Programmers with network engineering skills Owen DeLong (Mar 12)
- Re: Programmers with network engineering skills Jeroen van Aart (Mar 12)
- Re: Programmers with network engineering skills Owen DeLong (Mar 12)
- Re: Programmers with network engineering skills Joe Greco (Mar 12)
- Re: Programmers with network engineering skills Mark Andrews (Mar 12)
- Re: Programmers with network engineering skills Joe Greco (Mar 13)
- Re: Programmers with network engineering skills Jimmy Hess (Mar 16)
- Re: Programmers with network engineering skills Jeroen van Aart (Mar 12)
- Re: Programmers with network engineering skills Aled Morris (Mar 13)
- Re: Programmers with network engineering skills Joe Greco (Mar 13)
- Re: Programmers with network engineering skills Steve Bertrand (Mar 13)
- Re: Programmers with network engineering skills Jeroen van Aart (Mar 16)
- Re: Programmers with network engineering skills Keegan Holley (Mar 12)
- Re: Programmers with network engineering skills Paul Graydon (Mar 12)