[QUESTION] Emails cannot start with underscore

[Nicolas Schwartau]

New bug checklist

• I have updated truemail to the latest version
• I have read the Contribution Guidelines
• I have read the documentation
• I have searched for existing GitHub issues

Bug description

Hello,

we noticed that emails starting with an underscore are considered invalid by this gem due to the regex check failing. A quick search lead us to the following discussion https://stackoverflow.com/a/9201006 which indicates that leading underscores should be considered valid.

We saw this is not supposed to follow the standard 100% but could the regex be updated? What do you think?

Complete output when running truemail, including the stack trace and command used

Truemail.validate("[e-mail]")
=>
<Truemail::Validator:
 @result=
  #<struct Truemail::Validator::Result
   success=false,
   email="[e-mail]",
   domain="example.com",
   mail_servers=[],
   errors={:regex=>"email does not match the regular expression"},
   smtp_debug=nil,
   configuration=
    #<Truemail::Configuration:
     @blacklisted_domains=[],
     @blacklisted_mx_ip_addresses=[],
     @connection_attempts=2,
     @connection_timeout=2,
     @default_validation_type=:mx,
     @dns=[],
     @email_pattern=/(?=\A.{6,255}\z)(\A([\p{L}0-9]+[\w\p{L}.+!~,'&%#*^`{}|\-\/?=$]*)@((?i-mx:[\p{L}0-9]+([\-.]{1}[\p{L}0-9]+)*\.\p{L}{2,63}))\z)/,
     @not_rfc_mx_lookup_flow=false,
     @response_timeout=2,
     @smtp_error_body_pattern=/(?=.*550)(?=.*(user|account|customer|mailbox)).*/i,
     @smtp_fail_fast=false,
     @smtp_port=25,
     @smtp_safe_check=false,
     @validation_type_by_domain={},
     @verifier_domain="example.com",
     @verifier_email="[e-mail]",
     @whitelist_validation=false,
     @whitelisted_domains=[]>>,
 @validation_type=:mx>

[Vladislav Trotsenko]

Hi, @NicolasSch! Thanks for your request. I think it's not a bug. And default regex it is just my propose. You can configure any behaviour of regex validation you want. Honestly, I've never seen real email addresses that start from special characters.