Fix for postfix not launching reliably at boot time

[Bill Cole]

On 29 Nov 2020, at 6:02, Gerben Wierda via macports-users wrote:

> I think I shared this before, but I’m not certain so I am doing so 
> now (again).
>
> The MacPorts postfix master process will not launch reliably at boot 
> if it is set up with ‘port load postfix’. The reason for the 
> unreliable boot is that macOS during boot for about 60 seconds or so 
> claims port 25 (and 587) because it launches its own postfix, then 
> quickly kills it. When Apple’s postfix master launches first (there 
> is no control in launchd what launches first) this can block the 
> MacPorts version, which then fails.
>
> By changing /etc/postfix/master.cf of Apple’s postfix the boot by 
> MacPorts launches reliably.
>
> This means patching Apple’s files, which I frown upon, but I’m 
> still using Mojave and I think Apple updates leave master.cf alone and 
> macOS itself doesn’t really use postfix, it is a leftover. I don’t 
> know if this is still possible in later versions of macOS. If it 
> isn’t because Apple has locked these down, a more intelligent 
> startup command could be written that works around this macOS 
> behaviour.

Another approach is to boot into "Recovery Mode" and disable the launchd 
startup:

    launchctl unload -w 
/System/Library/LaunchDaemons/com.apple.postfix.master.plist

If you've persistently disabled SIP (which you really shouldn't...) you 
can do that as root without booting into Recovery Mode.

-- 
Bill Cole
bill at scconsult.com or billcole at apache.org
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire