github.com: grade B (3 pass, 2 warn, 0 fail) in 1.279s

pass  MX records 0 github-com.mail.protection.outlook.com
pass  STARTTLS   1 of 1 offer TLS with a valid certificate
warn  SPF        ~all, 10 of 10 lookups
      see https://kirkdiamond.com/guides/spf-10-dns-lookup-limit
pass  DMARC      p=quarantine
warn  DKIM       cm, google, k1, k2, k3, s1, s2, selector1, zendesk1, zendesk2
      see https://kirkdiamond.com/guides/spf-vs-dkim-vs-dmarc
info  MTA-STS    not published
      see https://kirkdiamond.com/guides/mta-sts-explained
info  TLS-RPT    not published
      see https://kirkdiamond.com/guides/mta-sts-explained

mx (MX)
    0 github-com.mail.protection.outlook.com   starttls=yes TLS 1.3 cert=valid

spf (10 lookups, 0 void)
  github.com: v=spf1 ip4:192.30.252.0/22 include:spf.protection.outlook.com include:_netblocks.google.com include:_netblocks2.google.com include:mail.zendesk.com include:_spf.salesforce.com include:servers.mcsv.net include:mktomail.com include:sendgrid.net ip4:62.253.227.114 ip4:166.78.69.169 ip4:166.78.69.170 ip4:166.78.71.131 ~all
    spf.protection.outlook.com: v=spf1 ip4:40.92.0.0/15 ip4:40.107.0.0/16 ip4:52.100.0.0/15 ip4:52.102.0.0/16 ip4:52.103.0.0/17 ip4:104.47.0.0/17 ip6:2a01:111:f400::/48 ip6:2a01:111:f403::/49 ip6:2a01:111:f403:8000::/51 ip6:2a01:111:f403:c000::/51 ip6:2a01:111:f403:f000::/52 -all
    _netblocks.google.com: v=spf1 ip4:74.125.0.0/16 ip4:209.85.128.0/17 ~all
    _netblocks2.google.com: v=spf1 ip6:2001:4860:4000::/36 ip6:2404:6800:4000::/36 ip6:2607:f8b0:4000::/36 ip6:2800:3f0:4000::/36 ip6:2a00:1450:4000::/36 ip6:2c0f:fb50:4000::/36 ~all
    mail.zendesk.com: v=spf1 ip4:103.151.192.0/23 ip4:185.12.80.0/22 ip4:188.172.128.0/20 ip4:192.161.144.0/20 ip4:216.198.0.0/18 ~all
    _spf.salesforce.com: v=spf1 exists:%{i}._spf.mta.salesforce.com -all
    servers.mcsv.net: v=spf1 ip4:205.201.128.0/20 ip4:198.2.128.0/18 ip4:148.105.0.0/16 -all
    mktomail.com: v=spf1 ip4:199.15.212.0/22 ip4:72.3.185.0/24 ip4:72.32.154.0/24 ip4:72.32.217.0/24 ip4:72.32.243.0/24 ip4:94.236.119.0/26 ip4:37.188.97.188/32 ip4:185.28.196.0/22 ip4:192.28.128.0/18 ip4:103.237.104.0/22 ip4:130.248.172.0/24 ip4:130.248.173.0/24 ~all
    sendgrid.net: v=spf1 ip4:167.89.0.0/17 ip4:208.117.48.0/20 ip4:50.31.32.0/19 ip4:198.37.144.0/20 ip4:198.21.0.0/21 ip4:192.254.112.0/20 ip4:168.245.0.0/17 ip4:149.72.0.0/16 ip4:159.183.0.0/16 ip4:134.128.64.0/18 ip4:159.26.176.0/20 include:ab.sendgrid.net ~all
      ab.sendgrid.net: v=spf1 ip4:223.165.113.0/24 ip4:223.165.115.0/24 ip4:223.165.118.0/23 ip4:223.165.120.0/23 ~all

dmarc
  v=DMARC1; p=quarantine; sp=reject; pct=100; rua=mailto:dmarc@github.com; ruf=mailto:dmarc@github.com; fo=1

dkim cm: rsa 1024 bit

dkim google: rsa 2048 bit

dkim k1: rsa 1024 bit

dkim k2: rsa 2048 bit

dkim k3: rsa 2048 bit

dkim s1: rsa 2048 bit

dkim s2: rsa 2048 bit

dkim selector1: rsa 1024 bit

dkim zendesk1: rsa 2048 bit

dkim zendesk2: rsa 2048 bit