Regular Expressions 101

Pro

Group 1((?:\.|^).)?

?repeats the group contents below at most once:

Non-Capturing Group(?:\.|^)

1st Alternative\.

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

2nd Alternative^

^start of line

.any character (except for line terminators)

Positive Lookahead(?=.*@)

.*any character (except for line terminators), repeated any number of times

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Global pattern flags

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

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

Detailed match information will be displayed here automatically.

25 tokens

((?:\.|^).)?.(?=.*@)

New

captain.am-e-r-ica@email.com
my-cutie.pie+here@email.com
tom.cat@email.com
cutie.pie@email.com
captain.america@email.com

$1*

captain.am-e-r-ica@email.com
my-cutie.pie+here@email.com
tom.cat@email.com
cutie.pie@email.com
captain.america@email.com