SMTP Field Manual
Raw bounce and deferral replies from major mailbox providers and spam filters, with a plain-language note under each one.
SMTP reply codes
4xx is temporary. 5xx is permanent for that recipient or message.
Email providers
23 mailbox providers
Googlegmail.com, googlemail.com
Yahoo Incyahoo.com, aol.com
AT&Tatt.net, sbcglobal.net
Comcastcomcast.net
Appleicloud.com, me.com
Mail.rumail.ru
Outlookhotmail.com, outlook.com
Yandexyandex.com
Zohozoho.com
Rambler
Amazon Simple Email Service
Free
GoDaddy
GMX
Hey
Orange
QQ
Rackspace
Infomaniak
Hostpoint
ProtonMail
ImprovMX
Web.de
Spam filters
9 security gateways
Need deeper Gmail, Yahoo, Apple, or Outlook fix playbooks? See the provider bounce playbooks.
Response catalog adapted from the MIT-licensed SMTP Field Manual by ActiveCampaign / Postmark.