used https://ssl-config.mozilla.org/ to generate recommended
ciphers config for dovecot and postfix.
postfix set to use medium ciphers due to possibility of smtp
servers not being updated to latest.
MR !9
Mail server should only relay mail for domains and users it hosts. default is to reject.
Rules and order as follows:
1. reject_non_fqdn_recipient
Require the recipient to be in FQDN format for relaying
and routing reasons including locating user.
2. permit_auth_destination
Only accept mail to be routed if authorized.
3. reject
Don't accept any further mail for relaying.
MR !7
Filter mail based on recipient restrictions. default is to filter then
reject the remaining.
This is a default rule and submission requires it's own rule specified.
rules and order as follows:
1. permit_mynetworks
Allow local mail host to send to whomever.
2. reject_non_fqdn_recipient
must use a FQDN so that the recipient can be identified.
3. reject_unknown_recipient_domain
Only accept mail for the domains we host.
4. reject_unauth_destination
reject mail for domains we don't host and before any policy
checks are done. This prevents additional processes from
spawning that would otherwise be unused.
5. check_policy_service,unix:private/policyd-spf
bounce the mail that fails spf check. likely to be a non-smtp
server.
6. check_policy_service unix:private/quota
Check the recipients quota before delivery. if fails, bounce
the mail.
7. permit_auth_destination
Only accept mail for domains we host. This rule placed after
the bounces, so that filtering can be done first.
8. reject
Hard reject as the recipient doesn't belong to this host.
MR !7
Default is to accept all mail from sender after filtering.
smtpd_sender_restrictions rules and order are as follows:
1. permit_mynetworks
permit my network (localhost). Placed first as sometimes the
sender will not be a FQDN sender. (i.e. cron)
2. reject_non_fqdn_sender
bounce mail where sender not in format of FQDN.
3. reject
Reject all remaining senders
MR !7
Default is permit.
Rule order as follows:
1. permit_mynetworks
My network (localhost) is exempt from restriction
2. reject_invalid_helo_hostname
Don't allow a connection from an invalid host.
3. permit
Allow the remaining hosts not booted.
MR !7
Default is reject.
order of rules as follows:
1. reject_unauth_destination
if postfix doesn't own the destination, bounce
2. reject_unauth_pipelining
not punch through commands.
3. permit_mynetworks,
set as rule 3 after the above rejects, so that if a rouge
process on the server attempts to send, it is blocked.
4. permit_auth_destination,
Only accept a connection if the mailserver is the destination.
5. reject
Reject all remaining mail as it's clearly not for this host.
MR !7
Default config is for domain example.org, which
is the testing domain.
User will be required to customise '90-dkim' with thier
own domain configuration, including generating dkim signing certificates.
MR !2
