regex101: PCRE2 (PHP) Match Workspace

Non-Capturing Group(?:^|(?<=\s))

1st Alternative^

^start of line

2nd Alternative(?<=\s)

Positive Lookbehind(?<=\s)

\sany whitespace character

Negative Lookahead(?!1?\d{10}@)

1?optionally matches the literal 1 (49₁₀ / 61₈ / 31₁₆)

\d{10}a digit, repeated exactly 10 times

@the literal @ (64₁₀ / 100₈ / 40₁₆)

Group 1(\w[\w\.]*@\w+\.[\w\.]+)

\wany word character

Character Class[\w\.]*

*matches any number of characters from the set below:

\wany word character

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

@the literal @ (64₁₀ / 100₈ / 40₁₆)

\w+any word character, repeated at least once

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[\w\.]+

+matches at least one character from the set below:

\wany word character

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

\ban ASCII word boundary

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

25 tokens

Regular Expression

(?:^|(?<=\s))(?!1?\d{10}@)(\w[\w\.]*@\w+\.[\w\.]+)\b

New

123456789@test.com // allowed (9 digits or less)
01234567890@test.com // allowed (11 digits but not starting with 1)
123456789012@test.com // allowed (12 digits or more)

0123456789@test.com // NOT allowed (10 digits)
11234567890@test.com // NOT allowed (11 digits and starting with 1)

Extraction

123456789@test.com // allowed (9 digits or less)
01234567890@test.com // allowed (11 digits but not starting with 1)
123456789012@test.com // allowed (12 digits or more)

0123456789@test.com // NOT allowed (10 digits)
11234567890@test.com // NOT allowed (11 digits and starting with 1)