図書館からの予約資料連絡メールが届かない方へ
https://library.city.izumisano.lg.jp/topic/mail_error.html
1. whois
ed.city.izumisano.osaka.jp. 300 IN A 210.189.169.7 ed.city.izumisano.osaka.jp. 300 IN MX 10 mail.ed.city.izumisano.osaka.jp. mail.ed.city.izumisano.osaka.jp. 300 IN A 153.231.253.10 逆引きなし。 10.253.231.153.in-addr.arpa. 21600 IN CNAME 10.8.253.231.153.in-addr.arpa
2. history
ed.city.izumisano.osaka.jp. 300 IN TXT "v=spf1 +ip4:153.231.253.10/32 ~all" $ telnet 153.231.253.10 25 Trying 153.231.253.10... Connected to 153.231.253.10. Escape character is '^]'. 220 IZSK19OML-01.ed.city.izumisano.osaka.jp ESMTP Postfix EHLO wk.qmail.jp 250-IZSK19OML-01.ed.city.izumisano.osaka.jp 250-PIPELINING 250-SIZE 20480000 250-VRFY 250-ETRN 250-ENHANCEDSTATUSCODES 250-8BITMIME 250 DSN