regex101: Email Regex

Explanation

Pro

^start of line

Group 1([\w-\.+]+)

Character Class[\w-\.+]+

+matches at least one character from the set below:

\wany word character

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

+the literal + (43₁₀ / 53₈ / 2B₁₆)

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Group 2((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))

1st Alternative(\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)

Group 3(\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Character Class[0-9]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[0-9]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative(([\w-]+\.)+)

Group 4(([\w-]+\.)+)

Group 5([\w-]+\.)+

+repeats the group contents below at least once:

Character Class[\w-]+

+matches at least one character from the set below:

\wany word character

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 6([a-zA-Z]{2,4}|[0-9]{1,3})

1st Alternative[a-zA-Z]{2,4}

Character Class[a-zA-Z]{2,4}

{2,4}matches between 2 and 4 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

2nd Alternative[0-9]{1,3}

Character Class[0-9]{1,3}

{1,3}matches between 1 and 3 characters from the set below:

0-9one character from 0 (48₁₀) to 9 (57₁₀)

Group 7(\]?)

\]?optionally matches the literal ] (93₁₀ / 135₈ / 5D₁₆)

$end of line

Global pattern flags

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

g modifier: global. Finds all matches instead of stopping after the first

Quick Reference

26 tokens

Regular Expression

^([\w-\.+]+)@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$

Invalid:
mkyong
mkyong123@.com
mkyong()*@gmail.com
mkyong@%*.com
mkyong..2002@gmail.com
mkyong.@gmail.com
mkyong@mkyong@gmail.com
mkyong@gmail.com.1a

Valid:
mkyong@yahoo.com
mkyong-100@yahoo.com
mkyong.100@yahoo.com
mkyong111@mkyong.com
mkyong-100@mkyong.net
mkyong.100@mkyong.com.au
mkyong@1.com
mkyong@gmail.com.com
mkyong-100@yahoo-test.com
a.a@ac.cc.cc
mkyong@fdg
.dgfsdfg@dgf.dfg
mkyong+123@df.com
firstname+lastname@domain.com