Some inconsistencies with detection of email addresses in postgres

postgresql-email-inconsistencies

# select version();
                                            version
-------------------------------------------------------------------------------------------------
PostgreSQL 9.5.3 on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 4.8.2-19ubuntu1) 4.8.2, 64-bit
(1 row)

# SELECT email, to_tsvector('simple', email) FROM (
  VALUES  ('foo@example.com'), ('foo+123@example.com'),
          ('123+foo@example.com'), ('123+123foo@example.com'),
          ('foo123@example.com'), ('foo_123@example.com'),
          ('foo__123@example.com')
) as t (email);

         email          |             to_tsvector
------------------------+--------------------------------------
 foo@example.com        | 'foo@example.com':1
 foo+123@example.com    | '+123':2 'example.com':3 'foo':1
 123+foo@example.com    | '123':1 'foo@example.com':2
 123+123foo@example.com | '+123':2 '123':1 'foo@example.com':3
 foo123@example.com     | 'foo123@example.com':1
 foo_123@example.com    | 'foo_123@example.com':1
 foo__123@example.com   | '123':2 'example.com':3 'foo':1
 
 
 # select ts_debug('foo@example.com');
                                 ts_debug
---------------------------------------------------------------------------
 (email,"Email address",foo@example.com,{simple},simple,{foo@example.com})
(1 row)

# select ts_debug('foo+123@example.com');
                              ts_debug
---------------------------------------------------------------------
 (asciiword,"Word, all ASCII",foo,{english_stem},english_stem,{foo})
 (int,"Signed integer",+123,{simple},simple,{+123})
 (blank,"Space symbols",@,{},,)
 (host,Host,example.com,{simple},simple,{example.com})
(4 rows)

# select ts_debug('123+foo@example.com');
                                 ts_debug
---------------------------------------------------------------------------
 (uint,"Unsigned integer",123,{simple},simple,{123})
 (blank,"Space symbols",+,{},,)
 (email,"Email address",foo@example.com,{simple},simple,{foo@example.com})
(3 rows)

# select ts_debug('123+123foo@example.com');
                                 ts_debug
---------------------------------------------------------------------------
 (uint,"Unsigned integer",123,{simple},simple,{123})
 (int,"Signed integer",+123,{simple},simple,{+123})
 (email,"Email address",foo@example.com,{simple},simple,{foo@example.com})
(3 rows)

# select ts_debug('foo123@example.com');
                                    ts_debug
---------------------------------------------------------------------------------
 (email,"Email address",foo123@example.com,{simple},simple,{foo123@example.com})
(1 row)

# select ts_debug('foo_123@example.com');
                                     ts_debug
-----------------------------------------------------------------------------------
 (email,"Email address",foo_123@example.com,{simple},simple,{foo_123@example.com})
(1 row)

# select ts_debug('foo__123@example.com');
                              ts_debug
---------------------------------------------------------------------
 (asciiword,"Word, all ASCII",foo,{english_stem},english_stem,{foo})
 (blank,"Space symbols",__,{},,)
 (uint,"Unsigned integer",123,{simple},simple,{123})
 (blank,"Space symbols",@,{},,)
 (host,Host,example.com,{simple},simple,{example.com})
(5 rows)