ActiveState Code

Recipe 65215: E-mail Address Validation

This function simply validates an e-mail address. Ignore this recepie and go to my "StringValidator" recepie, which is a much better solution

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import re

def validateEmail(email):

	if len(email) > 7:
		if re.match("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$", email) != None:
			return 1
	return 0

Discussion

E-mail address validation is a pretty common thing when dealing with web forms. The reason I check if the length of "email" is greater than 7 is because to the best of my knowledge, no address can be shorter than 7 characters (ie. j@jj.ca).

See my "StringValidator" recepie for a much better solution!

Comments

  1. 1. At 2:47 p.m. on 18 aug 2001, Anonymous said:

    Short email adresses. It is important to note that email adresses _can_ be shorter than 7 characters. Although domain names shorter than 2 letters are not allowed in .com .net and .org, many ISO country domain registrars do allow one letter domain names. For example in Denmark, where I live. For example see http://www.n.dk

  2. 2. At 10:35 a.m. on 26 mar 2003, Stephen White said:

    Short email addresses and .va. If you'll do 'nslookup -type=mx va' or similar you'll find that va has mail exchangers associated. This means that the shortest email address, IMHO, is .

  3. 3. At 9:08 p.m. on 12 sep 2004, Peter Sanchez said:

    .info? Doesn't look like your code will validate .info domains. Here is the regexp I use for my email validation:

    re.compile('^[_.0-9a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,4}$')

  4. 4. At 3:17 a.m. on 20 sep 2005, Shekhar Tiwatne said:

    idn emails. I think this recepie may not validate idn email ids. Try validating user@zääz.de .

  5. 5. At 7:40 a.m. on 4 apr 2008, Rodolfo Puig said:

    Production Code. I've been using this regular expression for many years in various production environments (affiliate systems, forums, etc) and it hasn't given me any false positives. Enjoy...

    re.match("^[a-zA-Z0-9._%-]+@[a-zA-Z0-9._%-]+.[a-zA-Z]{2,6}$", email_str)

  6. 6. At 11:53 p.m. on 18 sep 2008, Timothee Besset said:

    that one in #5 will not accept john+doe@ and john-doe@

    I've modified it into:

    "^[a-zA-Z0-9._%-+]+@[a-zA-Z0-9._%-]+.[a-zA-Z]{2,6}$"

  7. 7. At 10:47 a.m. on 6 nov 2008, andreas.mock said:

    Hi all,

    just came across this recipe and read #5. Here is your false positive:

    haha.hoho.@somedomain.de

    is not a valid e-mail address. But the regex gives no false. Dots at the start and at the end of the local part are not allowed. See RFC2822.

    Best regards

    Andreas Mock

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