SMTP
- RFC5321: Simple Mail Transfer Protocol
- RFC5322: Internet Message Format
- RFC6409: Message Submission for Mail
- [Mailing Lists and Internationalized Email Addresses
- RFC6530: Overview and Framework for Internationalized Email
- RFC8314: Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access
RSPAMD
Problems & Solutions
SPF issues
- EHLO miss-match between announced name, IP and reverse
- missing TXT SPF record for the announced EHLO name
Example: if MX is smtp.vacs.fr
- reverse DNS of server IP must be smtp.vacs.fr
- there must be a TXT record 'smtp.vacs.fr' with v=spf1 a mx -all
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