regex101: Email Last Hop v6

Pro

Non-Capturing Group(?:\s*from\s(?:(?:([^$\n]*?)\s)|(\[[^\]]*\]))?(?:\((?:(?:((?!HELO|EHLO)[^\s]*)|(?:(?:EHLO)|(?:HELO)))?(?:[\s\w\.]*(?:(?:\[([^\]]*)\])|([^$\s]*))\))))?(?:\{.*\})?)?

?repeats the group contents below at most once:

\s*any whitespace character, repeated any number of times

fromthe literal text from (case sensitive)

\sany whitespace character

Non-Capturing Group(?:(?:([^\(\n]*?)\s)|(\[[^\]]*\]))?

?repeats the group contents below at most once:

1st Alternative(?:([^\(\n]*?)\s)

Non-Capturing Group(?:([^\(\n]*?)\s)

Group 1([^\(\n]*?)

Negated Character Class[^\(\n]*?

*?matches any number of characters outside the set below:

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

\na line-feed (newline) character (ASCII 10)

\sany whitespace character

2nd Alternative(\[[^\]]*\])

Group 2(\[[^\]]*\])

\[the literal [ (91₁₀ / 133₈ / 5B₁₆)

Negated Character Class[^\]]*

*matches any number of characters outside the set below:

\]the literal ] (93₁₀ / 135₈ / 5D₁₆)

Non-Capturing Group(?:$(?:(?:((?!HELO|EHLO)[^\s]*)|(?:(?:EHLO)|(?:HELO)))?(?:[\s\w\.]*(?:(?:\[([^\]]*)\])|([^$\s]*))\))))?

?repeats the group contents below at most once:

\(the literal ( (40₁₀ / 50₈ / 28₁₆)

Non-Capturing Group(?:(?:((?!HELO|EHLO)[^\s]*)|(?:(?:EHLO)|(?:HELO)))?(?:[\s\w\.]*(?:(?:\[([^\]]*)\])|([^\)\s]*))\)))

Non-Capturing Group(?:((?!HELO|EHLO)[^\s]*)|(?:(?:EHLO)|(?:HELO)))?

?repeats the group contents below at most once:

1st Alternative((?!HELO|EHLO)[^\s]*)

Group 3((?!HELO|EHLO)[^\s]*)

Negative Lookahead(?!HELO|EHLO)

1st AlternativeHELO

HELOthe literal text HELO (case sensitive)

2nd AlternativeEHLO

EHLOthe literal text EHLO (case sensitive)

Negated Character Class[^\s]*

*matches any number of characters outside the set below:

\sany whitespace character

2nd Alternative(?:(?:EHLO)|(?:HELO))

Non-Capturing Group(?:(?:EHLO)|(?:HELO))

1st Alternative(?:EHLO)

Non-Capturing Group(?:EHLO)

EHLOthe literal text EHLO (case sensitive)

2nd Alternative(?:HELO)

Non-Capturing Group(?:HELO)

HELOthe literal text HELO (case sensitive)

Non-Capturing Group(?:[\s\w\.]*(?:(?:\[([^\]]*)\])|([^\)\s]*))\))

Character Class[\s\w\.]*

Non-Capturing Group(?:(?:\[([^\]]*)\])|([^\)\s]*))

\)the literal ) (41₁₀ / 51₈ / 29₁₆)

Non-Capturing Group(?:\{.*\})?

\s*any whitespace character, repeated any number of times

Non-Capturing Group(?:(?:client\s)?[$\{\[]+([^$\}\]]*)[\)\}\]]+\;?(?:\{.*\})?)?

Non-Capturing Group(?:[\s\n]*)

Non-Capturing Group(?:\s*(?:by(?:(?:.*?)(?:\;|(?:[\r\n]+))))(?!.*with))?

Non-Capturing Group(?:\s*(?:by\s[^\;]*\)?)(?=.*with)\s*)?

Non-Capturing Group(?:with\s*(?:((?:[^\n;]*))(?:.*\;)?))?

Non-Capturing Group(?:[\s\n]*)?

Non-Capturing Group(?:$?envelope-from\s*([^\n]*)\;?$?)?

Non-Capturing Group(?:\s*id[^;]*\;?)?

Non-Capturing Group(?:[\s\n]*)?

Non-Capturing Group(?:for\s([^\;]*)\;)?

Non-Capturing Group(?:[\s\n]*)?

Non-Capturing Group(?:$.*$\;)?

Non-Capturing Group(?:[\s\n])?

Group 10([^\(]+)?

Non-Capturing Group(?:$?envelope-from\s*([^\n]*)\;?$?)?

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

x modifier: extended. Ignores unescaped whitespace and comments outside character classes

25 tokens

Regular Expression

(?:\s*from\s(?:(?:([^\(\n]*?)\s)|(\[[^\]]*\]))?(?:\((?:(?:((?!HELO|EHLO)[^\s]*)|(?:(?:EHLO)|(?:HELO)))?(?:[\s\w\.]*(?:(?:\[([^\]]*)\])|([^\)\s]*))\))))?(?:\{.*\})?)?
\s*(?:(?:client\s)?[\(\{\[]+([^\)\}\]]*)[\)\}\]]+\;?(?:\{.*\})?)?
(?:[\s\n]*)
(?:\s*(?:by(?:(?:.*?)(?:\;|(?:[\r\n]+))))(?!.*with))?
(?:\s*(?:by\s[^\;]*\)?)(?=.*with)\s*)?
(?:with\s*(?:((?:[^\n;]*))(?:.*\;)?))?
(?:[\s\n]*)?
(?:\(?envelope-from\s*([^\n]*)\;?\)?)?
(?:\s*id[^;]*\;?)?
(?:[\s\n]*)?
(?:for\s([^\;]*)\;)?
(?:[\s\n]*)?
(?:\(.*\)\;)?(?:[\s\n])?
([^\(]+)?
(?:\(?envelope-from\s*([^\n]*)\;?\)?)?

Unit Tests

There are no unit tests, click to add some.