Mail Administration
See also:
- automatic discovery of mail server settings for clients
DNS
see also: DNS
SPF
Allow server in A record, allow server in MX record, disallow all others.
v=spf1 +a +mx -all
DKIM
DMARC
example
put into TXT record _dmarc.example.com:
v=DMARC1; p=none; rua=mailto:postmaster@example.com; ruf=mailto:postmaster@example.com;
Tools
Servers
Postfix (MTA)
| echo mail queue | mailq |
|---|---|
| read mail | postcat -q MESSAGE_ID |
| delete delayed mails | postsuper -d ALL deferred |
| delete queue | postsuper -d ALL |
more information: Postfix Queue Management
exim4 (MTA)
| echo mail queue | exim -bp |
|---|---|
| delete frozen mails | exiqgrep -iz|xargs exim -Mrm |
Dovecot (LDA)
Postmaster
| Outlook | postmaster.outlook.com |
|---|---|
| Google Postmaster Tools |
Spam detection
Office 365 / Outlook.com / Hotmail
Office Blacklist: https://sender.office.com/
Outlook.com anti-spam mechanisms: https://sendersupport.olc.protection.outlook.com/pm/services.aspx
SNDS: https://sendersupport.olc.protection.outlook.com/snds/index.aspx
If you send through an SMTP Smart Relay through Office 365, you might need to include the IP address you're sending from (not only the Microsoft servers, but your own SMTP server) in the SPF records.
Test
Online tools
- Internet.NL – tests for IPv6, DNSSEC, DMARC, DKIM, SPF and STARTTLS
- SSL-Tools – checks if mail server uses STARTTLS for mail delivery
- MX Toolbox – checks mail deliverability (DMARC, SPF, DKIM)
- Is Not Spam – SPF, Sender-ID, DomainKeys, DKIM, SpamAssassin Check