Reg.Exp to validate Email Address

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks!
Here is a question, what is your opinion about validating an email address using this regular expression:


         if($email=~ /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$/i){
         
         print "ok";
         
         }else{ print "bad";}
[download]

Is there any obvious or possible security issue(s) by using this regular expression, or it is just OK? Does anyone know any other way, or a better regular expression I could use?
Thanks for the help!

Comment on Reg.Exp to validate Email Address Download Code

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Re: Reg.Exp to validate Email Address by Limbic~Region (Chancellor) on Jan 07, 2009 at 19:35 UTC
Anonymous Monk, As merlyn points out, this is broken - consider: `.@..ZZZZ` [download] It is an extremely common mistake to assume what is a valid email SMTP address due to ignorance of the RFC. You should use Email::Valid if your purpose is to determine if a string is a valid formatted SMTP email address (don't know of one that does UUCP or X.400 or CC:Mail email addresses). On the other hand, if your purpose is to specifically look for strings that, while technically valid, are strings you do not want to accept (due to attempting to exploit an open relay for instance), then you need to be very explicit in what your requirements are and we will try to help. Update: It may be inconceivable to some as to why I would advocate not using Email::Valid in certain circumstances. Here is a short list of nodes that may be worth reading: •Re^5: Please evaluate: RegEx for validating e-mail addresses Practical e-mail address validation Re: Breaking The Rules Re: Re: Re: Re: regex to validate e-mail addresses and phone numbers Cheers - L~R	[reply] [d/l]
Re: Reg.Exp to validate Email Address by merlyn (Sage) on Jan 07, 2009 at 19:13 UTC
It's broken. Please see perlfaq9 under "How do I check a valid mail address?". -- Randal L. Schwartz, Perl hacker	[reply]
Re: Reg.Exp to validate Email Address by zentara (Cardinal) on Jan 07, 2009 at 19:19 UTC
regexp to only allow for formally valid email addresses I'm not really a human, but I play one on earth Remember How Lucky You Are	[reply]