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Simple email expression. Doesn't allow numbers in the domain name and doesn't allow for top level domains that are less than 2 or more than 3 letters (which is fine until they allow more). Doesn't handle multiple "." in the domain ([email protected]).

Domain names: This regular expression tests the validity of a domain or hostname. It will match any valid domain name that does not contain characters which are invalid in URLs, and which ends in .com, .org, .net, .mil, or .edu. You can add additional valid TLDs by appending the | (pipe) character and the desired TLD to the list in the parens.

Checks domain names. This is an attempt to deal with some of the issues of the other reg ex in not handling leading periods(.) and hypens(-).

Modified URL RegExp that requires (http, https, ftp)://, A nice domain, and a decent file/folder string. Allows : after domain name, and these characters in the file/folder sring (letter, numbers, - . _ ? , ' / \ + & % $ # = ~). Blocks all other special characters-good for protecting against user input!

Host/Domain name validation for perl. Should be combined with a check for length <= 63 characters and that $2 is in a list of top-level domains.

Most email validation regexps are outdated and ignore the fact that domain names can contain any foreign character these days, as well as the fact that anything before @ is acceptable. The only roman alphabet restriction is in the TLD, which for a long time has been more than 2 or 3 chars (.museum, .aero, .info). The only dot restriction is that . cannot be placed directly after @. This pattern captures any valid, reallife email adress.

Matches a valid email address including ip's which are rarely used. Allows for a-z0-9_.- in the username, but not ending in a full stop i.e [email protected] is invalid and a-z0-9- as the optional sub domain(s) with domain name and a 2-7 char (a-z) tld allowing for short tld's like ca and new ones like museum.

Is used to evaluating domain names, none of the extras such as paths or protocols.

does not allow IP for domain name : [email protected] does not allow litteral addresses "hello, how are you?"@world.com allows numeric domain names after the last "." minimum 2 letters

Based of from Steward Haddock's domain nam Checks domain names. This is an attempt to deal with some of the issues of the other reg ex in not handling leading periods(.), hypens(-). and valid extension.

Checks domain names. This validates domains based on latest specifications (RFCs 952 and 1123 dealing with hostnames and RFC 1035 dealing with domain name system requirements) except that it only includes realistic fully-qualified domains: 1. requires at least one subdomain 2. allows shortest top-level domains like "ca", and "museum" as longest. Other validation rules: 1. Labels/parts should be seperated by period. 2. Each label/part has maximum of 63 characters. 3. First and last character of label must be alphanumeric, other characters alphanumeric or hyphen. 4. Does not check maxlength of domain which incidentally is 253 characters of text (255 binary representation). For a regular expression that matches ALL domains: ^([a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?\.)*[a-zA-Z0-9]([a-zA-Z0-9\-]{0,61}[a-zA-Z0-9])?$

regex to validate email address noteworthy: (1) It allows usernames with 1 or 2 alphanum characters, or 3+ chars can have -._ in the middle. username may NOT start/end with -._ or any other non alphanumeric character. (2) It allows heirarchical domain names (e.g. [email protected]). Similar -._ placement rules there. (3) It allows 2-9 character alphabetic-only TLDs (that oughta cover museum and adnauseum :>). (4) No IP email addresses though -- I wouldn't Want to accept that kind of address.

UK domain names. Includes the following restrictions from Nominet as at time of posting: 1.Only a-z, 0-9 and hyphen may be used. 2.First or last character may not be a hyphen. 3.Third and fourth characters may not both be hyphens. 4.Third level domain may not be a single character. 5.Third level domain may not be two letters or two numbers. 6.Third level domain may be one letter and one number. This does not yet include the following restrictions: 1.Whole domain may not be longer than 64 characters in length. 2.Third level domain may not duplicate any top/second level domain.

UK domains with protocol for http/https/ftp. Based on my previous expression, this allows the subdomain "www" for the http/https protocols, or "ftp" for the ftp protocol only.

This accepts RFC 2822 email addresses in the form:<br> [email protected] OR<br> Blah &lt;[email protected]&gt;<br> <br> RFC 2822 email 'mailbox':<br> mailbox = name-addr | addr-spec<br> name-addr = [display-name] "<" addr-spec ">"<br> addr-spec = local-part "@" domain<br> domain = rfc2821domain | rfc2821domain-literal<br> <br> local-part conforms to RFC 2822.<br> <br> domain is either:<br> An rfc 2821 domain (EXCEPT that the final sub-domain must consist of 2 or more letters only).<br> OR<br> An rfc 2821 address-literal.<br> (Note, no attempt is made to fully validate an IPv6 address-literal.)<br> <br> Notes:<br> This pattern uses (.NET/Perl only?) features named group "(?&lt;name&gt;)" and alternation/IF (?(name)).<br> <br> See <a href="http://regexadvice.com/forums/permalink/26742/26742/ShowThread.aspx#26742">this regexadvice.com thread</a> for more info, including a version that does not use .NET features.<br> <br> RFC 2822 (and 822) do allow embedded comments, whitespace, and newlines within *some* parts of an email address, but this pattern above DOES NOT.<br> <br> RFC 2822 (and 822) allow the domain to be a simple domain with NO ".", but this pattern requires a compound domain at least one "." in the domain name, as per RFC 2821 (4.1.2).<br> <br> RFC 2822 allows/disallows certain whitespace characters in parts of an email address, such as TAB, CR, LF BUT the pattern above does NOT test for these, and assumes that they are not present in the string (on the basis that these characters are hard to enter into an edit box).

UK http/https/ftp URI. Based on my previous expression, this one takes an optional port number and optional trailing slash.

The following pattern checks whether the input string is a valid email address in the form &quot;[email protected]&quot;. Actually, it does not have to be a &quot;.com&quot; address. Any combination of letters following the last period are fine. Also, the email name can have a dash or be separated by one or more periods. The Domain name can also have multiple words separated by periods. Thus, it will validate [email protected] and [email protected].

A short and sweet email address validator. Checks that the username starts and ends with an alphanumeric character, allows a few non-repeating 'special characters' (namely -, ., _, +, &amp;) and checks for a sensible domain name (2-6 character TLD required). Some unconventional, yet technically valid, addresses will not be matched, but this is only a simple expression ;-)

A simple regex which should validate a domain name according to RFC 1035 updated to match domain names with hyphens

Checks domain names. This will match all of the valid domains. It will accept TLD's that are from 2 to 6 characters. You can not have more then one dash or period next to each other. Also it will not let you have dashes at end of the words.