Rewrite "smartmatch" expression to avoid warning.

Perl 5.18 marked "smartmatch" as experimental and emits a warning.
This commit gets rid of "smartmatch" expression '$value ~~ @array'
Allow '=' character in user-part of email address.
Version 3.6

- Improved compatibility with perl < 5.10 and perl >= 5.18
- Added support for more chars in user-part of email address.