On 2026-02-18 at 13:00:05 UTC-0500 (Wed, 18 Feb 2026 19:00:05 +0100)
Daniel Azuelos via Postfix-users <[email protected]>
is rumored to have said:
Hello,
Postfix is installed by default on macOS ( here a Sequoia 15.7.3 ).
Yes, it is. But it is Apple's customized version and it is only
configured to be a "null client" that takes in mail via the sendmail
command and tries to deliver it
Modern macOS should not be used as a "server" platform of any sort.
Apple has done multiple things to make that infeasible and while you can
fight them, you cannot win. Modern Macs are *unfit* for server duty
using macOS.
But I have some tips anyway...
After a complete verification of /etc/postfix/main.cf &
/etc/postfix/master.cf
Verified how??? They can be syntactically correct but functionally
broken.
See
https://www.postfix.org/DEBUG_README.html#:~:text=help.-,reporting%20problems%20to%20postfix%[email protected]
for the information we need to help you.
and rewriting
/System/Library/com.apple.postfix.master.plist
( which is on a RO filesystem )
Actually /System/Library/LaunchDaemons/com.apple.postfix.master.plist
You need to *remove* that if you want to run a real mail server. That
means reboot to Recovery Mode, disable SIP, remove the .plist, re-enable
SIP, reboot.
on
/Library/com.apple.postfix.master.plist
( which is on a RW filesystem )
Again, missing a /LaunchDaemons/ directory level.
Note that you also need to write something very *different* from Apple's
plist and .cf files, which implement an on-demand null client without a
smarthost.
checking:
postfix check
postfix status...
Postfix is running, and I am able to send me a local email.
I also receive a lot of external emails.
I'm surprised that it works at all, if you didn't remove the System
launchctl plist and write a *correct* one, things will break.
But I get a lot of errors shown with:
postqueue -p
like:
B68F71C1C2A 256170 Tue Feb 17 14:05:38 [email protected]
(unknown mail
transport
error)
[email protected]
Since you are using Apple's customized Postfix, that could mean
anything...
Check your main.cf for directives related to transports, e.g.
smtp_transport_maps. Any transport used has to also have an entry in
master.cf.
And the worst of this problem is that postfix is not logging anything
in
/var/log/mail.log
which was my best source of help for 15 years managing Postfix.
Welcome to modern macOS.
I checked:
syslogd is running
and configured with:
/etc/asl/com.apple.mail
which contains:
# mail facility has its own log file
? [= Facility mail] claim only
> /var/log/mail.log mode=0644 format=bsd rotate=seq compress
file_max=5M all_max=50
* file /var/log/mail.log
which looks correct.
I see you are trusting Apple's in-system documentation, i.e. 'man'
pages. They lie. They are obsolete. ASL is obsolete. Since 10.12, the
new hotness in macOS logs is "Unified Logging" which does not do what
experienced sysadmins or POSIX-compliant software expect. Past APIs and
configurations no longer work. 'man asl.conf' might as well be a LLM
hallucination.
How to configure Postfix logging on recent versions of macOS?
1. Install a non-antique Postfix. As of 2024 and El Capitan on Intel,
the MacPorts build worked well. I do not know if they've been able to
keep current Postfix functioning on Sequoia or later. This also requires
disabling the built-in Postfix.
2. Enable Postfix's built-in file logging:
https://www.postfix.org/MAILLOG_README.html
The version of Postfix installed on macOS Sequoia is version 3.2.2.
It is a sad fact that in Sequoia, Apple shipped a version of Postfix
that its logging system can't support and which can't do its own
logging. You need 3.4.x for that.
This is more a macOS problem than a Postfix one.
Yes, it is.
I ran mail servers on Macs for 20+ years. It got progressively more of a
hassle to do that well after 10.6 (Snow Leopard) and when my last
machine that could run El Capitan (10.11) died for good, I moved to
FreeBSD.
Apple made a strategic choice decades ago to replace core subsystems of
BSD Unix with their own tools: first ASL and SystemStarter, later
Unified Logging and LaunchD. They do not want to support Macs as servers
so they don't bother.
--
Bill Cole
[email protected] or [email protected]
(AKA @[email protected] and many *@billmail.scconsult.com
addresses)
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