module CogiEmail

Normalize email address.

You need to validate before normalize an email address.

@param [String] email Email address

@return [String] Email address in lowercase, without special characters.

@raise [CogiEmail::NormalizationError] If can not normalize the email address.

@example

CogiEmail.normalize('(Peter Brown)<peter_brown@example.com>') # => peter_brown@example.com
CogiEmail.normalize('peter_brown@example.com') # => peter_brown@example.com
CogiEmail.normalize('Peter_Brown@example.com') # => peter_brown@example.com
CogiEmail.normalize('peter brown@example.com') # => peter_brown@example.com

   # File lib/cogi_email.rb
47 def self.normalize(email)
48   begin
49     m = Mail::Address.new(email)
50     m.address.downcase
51   rescue
52     raise CogiEmail::NormalizationError
53   end
54 end

Check if an email address is real or not.

An email address is real if:

Valid
Has MX DNS record
Can send test email

@param [String] email Email address

@return [Boolean] True if email address is real, otherwise False

@example

CogiEmail.real_email?('nobi.younet@gmail.com')   # => true
CogiEmail.real_email?('nobi.younet@example.com') # => false

    # File lib/cogi_email.rb
 93 def self.real_email?(email)
 94   return false unless self.validate?(email) # not a valid email address
 95   result = true
 96 
 97   begin
 98     v = CogiEmail::Checker.new(email)
 99     v.connect
100     v.verify
101   rescue
102     result = false
103   end
104 
105   result
106 end

Check if email domain is valid by making a DNS lookup.

An email domain is valid if it has an MX DNS record is set up to receive mail.

Reference: www.safaribooksonline.com/library/view/ruby-cookbook/0596523696/ch01s19.html

@param [String] email Email address

@return [Boolean] True if email domain have valid MX DNS record, otherwise False

   # File lib/cogi_email.rb
65 def self.valid_email_domain?(email)
66   valid = true
67 
68   begin
69     m = Mail::Address.new(email)
70     hostname = m.domain
71     Resolv::DNS.new.getresource(hostname, Resolv::DNS::Resource::IN::MX)
72   rescue Resolv::ResolvError
73     valid = false
74   end
75 
76   valid
77 end

Check if a string is a valid email address.

This library is so strict to ensure that all email is clean and deliverable.

References:

https://www.jochentopf.com/email/
https://fightingforalostcause.net/content/misc/2006/compare-email-regex.php

@param [String] email Email address

@return [Boolean] True if it is in a valid email, otherwise False

@example

CogiEmail.validate?('peter_brown@example.com') # => true
CogiEmail.validate?('peter-brown@example.com') # => true
CogiEmail.validate?('peter.brown@example.com') # => true
CogiEmail.validate?('peter brown@example.com') # => false
CogiEmail.validate?('peter_brown@@example.com') # => false

   # File lib/cogi_email.rb
27 def self.validate?(email)
28   pattern = /\A\s*([-\p{L}\d+._]{1,64})@((?:[-\p{L}\d]+\.)+\p{L}{2,})\s*\z/i
29   !!(email =~ pattern)
30 end