SPFを設定していても、Gmail 側で正しく検索される保証はない。
- メール送信がDNSに強く依存していることが分かる。
1. fail
108.177.97.26 failed after I sent the message. Remote host said: 550-5.7.26 This mail has been blocked because the sender is unauthenticated. 550-5.7.26 Gmail requires all senders to authenticate with either SPF or DKIM. 550-5.7.26 550-5.7.26 Authentication results: 550-5.7.26 DKIM = did not pass 550-5.7.26 SPF [m.qmail.jp] with ip: [157.7.113.173] = did not pass 550-5.7.26