^ asserts position at start of a line From:
matches the characters From: literally (case sensitive)\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
1st Capturing Group (\s[A-Za-z]+)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
2nd Capturing Group (\s[A-Za-z]+)?
? matches the previous token between zero and one times, as many times as possible, giving back as needed (greedy)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
\s matches any whitespace character (equivalent to [\r\n\t\f\v ])
< matches the character < with index 6010 (3C16 or 748) literally (case sensitive)
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
Match a single character present in the list below [A-Za-z]
+ matches the previous token between one and unlimited times, as many times as possible, giving back as needed (greedy)
A-Z matches a single character in the range between A (index 65) and Z (index 90) (case sensitive)
a-z matches a single character in the range between a (index 97) and z (index 122) (case sensitive)
@domain
matches the characters @domain literally (case sensitive)\. matches the character . with index 4610 (2E16 or 568) literally (case sensitive)
com>
matches the characters com> literally (case sensitive)g modifier: global. All matches (don't return after first match)
m modifier: multi line. Causes ^ and $ to match the begin/end of each line (not only begin/end of string)