v5.1.0p3

• Keep compatibility with the Go language version of Sisimai #311
  • There are some breaking changes at internal APIs
  • Sisimai::SMTP::Error has been renamed to Sisimai::SMTP::Failure and the following methods
    implemented:
    • is_temporary()
    • is_hardbounce()
    • is_softbounce()
    • soft_or_hard() has been removed
  • Changes in Sisimai::Rhost
    • get() method has been renamed to find()
    • Fix bug in code to check the domain part of an email address as a remote hostname
    • Add a new error message pattern: hosted tenant which has no mail-enabled subscriptions'
      in Sisimai::Rhost::Microsoft
  • Code improvement and bug fix at Sisimai::Lhost::Exim
    • Remove needless condition for getting error messages
    • Rewrite code for getting an SMTP reply code and a delivery status code
  • Add a new error message pattern in Sisimai::Reason::BadReputation
• Warn if Sisimai::Message.load method was called #302 #303
• Remove unused method Sisimai::Order.deault #304
• Fix bug in Sisimai::Message.tidy() method #305
• Code improvement in Sisimai::RFC5322 and Sisimai::ARF
• Fix the minimum and the maximum SMTP Reply code: 221 and 557 in Sisimai::SMTP::Reply
• Remove regular expressions from error message patterns at the following classes: #308
  • Sisimai::Reason::Blocked
  • Sisimai::Reason::MailerError
  • Sisimai::Reason::SpamDetected
• Fix typo in Sisimai::Rhost::YahooInc #310