Regex to Match Email address

Question

I have the below regex to match email address with atleast one @ and one .

[-0-9a-zA-Z.+_]+@[-0-9a-zA-Z.+_]+\.[a-zA-Z]{2,4}

Am wondering can it be simplified further to match email address with atleast one @ and one .?

• Veedrac: ex-parrot.com/~pdw/Mail-RFC822-Address.html and stackoverflow.com/a/201378/1763356
• Ruslan López: I know this isn't stack overflow but just wanted to point that your regex accepts _@_.aa as a valid mail so it's not for common cases :P

Answer 1

Simple Regular Expression for Email Addresses

[A-Z0-9._%+-]+@[A-Z0-9.-]+\\.[A-Z]{2,4}

is one of the simplest possible. In many cases this simple expression is good enough. It consists of five parts:

[A-Z0-9._%+-]+ - the first part of mail address may contain all characters, numbers, points, underscores, percent, plus and minus.

@ - the @ character is mandatory

[A-Z0-9.-]+ - the second part of mail address may contain all characters, numbers, points, underscores.

\. - the point is mandatory

[A-Z]{2,4} - the domain name may contain all characters. The number of characters is limited between 2 and 4.

OPTION 2:

^(.+)@(.+)$ 

This one is simplest and only cares about ‘@’ symbol. Before and after ‘@’ symbol, there can be any number of characters.if you want to validate point(.) add \. into regular expression.

• rolfl: FYI, your {2,4} limit is legacy... for example, see: annefrank.house.museum

Answer 2

There are many edge cases to e-mail address structure that you will exclude if you try the simplest approach.

One I use that accepts most of the reasonably acceptable e-mail address looks like:

^(?:[w!#$%&'*+-/=?^`{|}~]+.)*[w!#$%&'*+-/=?^`{|}~]+@(?:(?:(?:[a-zA-Z0-9](?:[a-zA-Z0-9-](?!.)){0,61}[a-zA-Z0-9]?.)+[a-zA-Z0-9](?:[a-zA-Z0-9-](?!$)){0,61}[a-zA-Z0-9]?)|(?:[(?:(?:[01]?d{1,2}|2[0-4]d|25[0-5]).){3}(?:[01]?d{1,2}|2[0-4]d|25[0-5])]))$

which is preferable to the supposedly correct one:

(?<user>(?:(?:[^ \t\(\)\<\>@,;\:\\\"\.\[\]\r\n]+)|(?:\"(?:(?:[^\"\\\r\n])|(?:\\.))*\"))(?:\.(?:(?:[^ \t\(\)\<\>@,;\:\\\"\.\[\]\r\n]+)|(?:\"(?:(?:[^\"\\\r\n])|(?:\\.))*\")))*)@(?<domain>(?:(?:[^ \t\(\)\<\>@,;\:\\\"\.\[\]\r\n]+)|(?:\[(?:(?:[^\[\]\\\r\n])|(?:\\.))*\]))(?:\.(?:(?:[^ \t\(\)\<\>@,;\:\\\"\.\[\]\r\n]+)|(?:\[(?:(?:[^\[\]\\\r\n])|(?:\\.))*\])))*)

Note that all of the following addresses are perfectly acceptable as e-mail addresses:

 "[email protected]",
 "Somebody{MiddleName}[email protected]",
 "abc.\"defghi\"[email protected]",
 "Someone@[192.168.0.1]",
 "[email protected]",
 "[email protected]",
 "[email protected]",
 "[email protected]",
 "user@[IPv6:2001:db8:1ff::a0b:dbd0]",
 "\"much.more unusual\"@example.com",
 "\"[email protected]\"@example.com",
 "\"very.(),:;<>[]\\\".VERY.\\\"very@\\ \\\"very\\\".unusual\"@strange.example.com",
 "0@a",
 "!#$%&'*+-/=?^_`{}|[email protected]",
 "\"()<>[]:,;@\\\\\\\"!#$%&'*+-/=?^_`{}| ~ ? ^_`{}|~.a\"@example.org",
 "\"\"@example.org",
 "postbox@com",

The first regex only accepts some of these - only the second accepts all.

See here for a very good narrative on the subject.

Answer 3

It's important to have fraud detection, use libraries, validate tld, etc. However, you can achieve the latter using a complicated regex found here:

[a-zA-Z0-9.!#$%&’*+/=?^_`{|}~-]+@[A-Za-z0-9.-]+\.+(xn--vermgensberatung-pwb|xn--vermgensberater-ctb|xn--clchc0ea0b2g2a9gcd|xn--w4r85el8fhu5dnra|travelersinsurance|northwesternmutual|xn--xkc2dl3a5ee0h|xn--mgberp4a5d4ar|xn--mgbai9azgqp6j|xn--bck1b9a5dre4c|xn--5su34j936bgsg|xn--3oq18vl8pn36a|xn--xkc2al3hye2a|xn--mgba7c0bbn0a|xn--fzys8d69uvgm|xn--nqv7fs00ema|xn--mgbc0a9azcg|xn--mgbaakc7dvf|xn--mgba3a4f16a|xn--lgbbat1ad8j|xn--kcrx77d1x4a|xn--i1b6b1a6a2e|sandvikcoromant|kerryproperties|americanexpress|xn--rvc1e0am3e|xn--mgbx4cd0ab|xn--mgbi4ecexp|xn--mgbca7dzdo|xn--mgbbh1a71e|xn--mgbb9fbpob|xn--mgbayh7gpa|xn--mgbaam7a8h|xn--mgba3a3ejt|xn--jlq61u9w7b|xn--h2breg3eve|xn--fiq228c5hs|xn--b4w605ferd|xn--80aqecdr1a|xn--6qq986b3xl|xn--54b7fta0cc|weatherchannel|kerrylogistics|cookingchannel|cancerresearch|bananarepublic|americanfamily|afamilycompany|xn--ygbi2ammx|xn--yfro4i67o|xn--tiq49xqyj|xn--h2brj9c8c|xn--fzc2c9e2c|xn--fpcrj9c3d|xn--eckvdtc9d|wolterskluwer|travelchannel|spreadbetting|lifeinsurance|international|xn--qcka1pmc|xn--ogbpf8fl|xn--ngbe9e0a|xn--ngbc5azd|xn--mk1bu44c|xn--mgbt3dhd|xn--mgbpl2fh|xn--mgbgu82a|xn--mgbab2bd|xn--mgb9awbf|xn--gckr3f0f|xn--8y0a063a|xn--80asehdb|xn--80adxhks|xn--45br5cyl|xn--3e0b707e|versicherung|scholarships|lplfinancial|construction|xn--zfr164b|xn--xhq521b|xn--w4rs40l|xn--vuq861b|xn--t60b56a|xn--ses554g|xn--s9brj9c|xn--rovu88b|xn--rhqv96g|xn--q9jyb4c|xn--pgbs0dh|xn--pbt977c|xn--nyqy26a|xn--mix891f|xn--mgbtx2b|xn--mgbbh1a|xn--kpu716f|xn--kpry57d|xn--kprw13d|xn--jvr189m|xn--j6w193g|xn--imr513n|xn--hxt814e|xn--h2brj9c|xn--gk3at1e|xn--gecrj9c|xn--g2xx48c|xn--flw351e|xn--fjq720a|xn--fct429k|xn--estv75g|xn--efvy88h|xn--d1acj3b|xn--czr694b|xn--cck2b3b|xn--9krt00a|xn--80ao21a|xn--6frz82g|xn--55qw42g|xn--45brj9c|xn--42c2d9a|xn--3hcrj9c|xn--3ds443g|xn--3bst00m|xn--2scrj9c|xn--1qqw23a|xn--1ck2e1b|xn--11b4c3d|williamhill|rightathome|redumbrella|progressive|productions|playstation|photography|olayangroup|motorcycles|lamborghini|kerryhotels|investments|foodnetwork|enterprises|engineering|creditunion|contractors|calvinklein|bridgestone|blockbuster|blackfriday|barclaycard|accountants|xn--y9a3aq|xn--wgbl6a|xn--wgbh1c|xn--unup4y|xn--pssy2u|xn--o3cw4h|xn--mxtq1m|xn--kput3i|xn--io0a7i|xn--fiqz9s|xn--fiqs8s|xn--fiq64b|xn--czru2d|xn--czrs0t|xn--cg4bki|xn--c2br7g|xn--9et52u|xn--9dbq2a|xn--90a3ac|xn--80aswg|xn--5tzm5g|xn--55qx5d|xn--4gbrim|xn--45q11c|xn--3pxu8k|xn--30rr7y|volkswagen|vlaanderen|vistaprint|university|telefonica|technology|tatamotors|swiftcover|schaeffler|restaurant|republican|realestate|prudential|protection|properties|onyourside|nextdirect|newholland|nationwide|mitsubishi|management|industries|immobilien|healthcare|foundation|extraspace|eurovision|cuisinella|creditcard|consulting|capitalone|boehringer|bnpparibas|basketball|associates|apartments|accountant|yodobashi|xn--vhquv|xn--tckwe|xn--p1acf|xn--nqv7f|xn--ngbrx|xn--l1acc|xn--j1amh|xn--j1aef|xn--fhbei|xn--e1a4c|xn--d1alf|xn--c1avg|xn--90ais|vacations|travelers|stockholm|statefarm|statebank|solutions|shangrila|scjohnson|richardli|pramerica|passagens|panasonic|microsoft|melbourne|marshalls|marketing|lifestyle|landrover|lancaster|ladbrokes|kuokgroup|insurance|institute|honeywell|homesense|homegoods|homedepot|hisamitsu|goodhands|goldpoint|furniture|fujixerox|frontdoor|fresenius|firestone|financial|fairwinds|equipment|education|directory|community|christmas|bloomberg|barcelona|aquarelle|analytics|amsterdam|allfinanz|alfaromeo|accenture|yokohama|xn--qxam|xn--p1ai|xn--node|xn--90ae|woodside|verisign|ventures|vanguard|uconnect|training|telecity|symantec|supplies|stcgroup|software|softbank|showtime|shopping|services|security|samsclub|saarland|reliance|redstone|property|plumbing|pictures|pharmacy|partners|observer|movistar|mortgage|merckmsd|memorial|mckinsey|maserati|marriott|lundbeck|lighting|jpmorgan|istanbul|ipiranga|infiniti|hospital|holdings|helsinki|hdfcbank|guardian|graphics|grainger|goodyear|frontier|football|firmdale|fidelity|feedback|exchange|everbank|etisalat|esurance|ericsson|engineer|download|discover|discount|diamonds|democrat|deloitte|delivery|computer|commbank|clothing|clinique|cleaning|cityeats|cipriani|chrysler|catholic|catering|capetown|business|builders|budapest|brussels|broadway|bradesco|boutique|baseball|bargains|barefoot|barclays|attorney|allstate|airforce|abudhabi|zuerich|youtube|yamaxun|xfinity|winners|windows|whoswho|wedding|website|weather|watches|wanggou|walmart|trading|toshiba|tiffany|tickets|theatre|theater|temasek|systems|surgery|support|storage|statoil|starhub|staples|spiegel|singles|shriram|shiksha|science|schwarz|schmidt|sandvik|samsung|rexroth|reviews|rentals|recipes|realtor|politie|pioneer|philips|panerai|origins|organic|oldnavy|okinawa|neustar|network|netflix|netbank|monster|metlife|markets|lincoln|limited|liaison|leclerc|latrobe|lasalle|lanxess|lancome|lacaixa|komatsu|kitchen|juniper|jewelry|ismaili|iselect|hyundai|hotmail|hoteles|hosting|holiday|hitachi|hangout|hamburg|guitars|grocery|godaddy|genting|gallery|fujit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This is useful because it invalidates against the very common typo of .con vs .com

• pacmaninbw: It is important that if you use code in an answer that it should be the same language as the question. The question was written about Java, not JavaScript. At the time the question was posted there may not have been the libraries you are referring to.