XPost: comp.os.linux.misc   
   From: lars@beagle-ears.com   
      
   On 2026-02-26, Rich  wrote:   
   > In comp.os.linux.misc Lars Poulsen  wrote:   
   >> On 2026-02-26, Lawrence D’Oliveiro  wrote:   
   >>> On Thu, 26 Feb 2026 00:36:32 -0000 (UTC), Lars Poulsen wrote:   
   >>>   
   >>>> But when my Windows PC that sits on the same LAN tries to submit   
   >>>> outgoing mail messages, they fail to go out. It appears that   
   >>>> postfix considers them prohibited relaying, even though they are   
   >>>> addressed to my own mailbox on my own local mail server.   
   >>>   
   >>>   
   >>>   
   >>> As a starting point, I assume you have “permit_mynetworks” listed in   
   >>> your “smtpd_relay_restrictions”. In which case, make sure your   
   >>> “mynetworks” sitting includes all the appropriate subnets for   
   >>> relaying, and only those.   
   >>>   
   >>> You can use the “postconf -p” to display all current configuration   
   >>> settings, whether explicit or defaulted.   
   >>   
   >> Thank you!!   
   >> I think this may have solved this problem, so now I can get to   
   >> see what the next blockage will be.   
   >>   
   >> As you know, "postconf -p" produces around 950 lines of output,   
   >> so unless you know what to "grep" for, you are lost.   
   >> I had read the hint in the comments in main.cf to look in   
   >> manual section postconf(5), but it does not mention permit_mynetworks   
   >>   
   >> I am puzzled, as to why this is not set by default. I thought this was   
   >> the reason why I was defining the list of mynetworks.   
   >   
   > mynetworks can't be "defaulted", because each site has a different   
   > network layout.  And if it were "defaulted" then postfix with that   
   > default would be an "open relay".  It (postfix) begins in "no relay"   
   > state, and you have to explicitly enable allowing such from parts of   
   > your network setup you want to allow.   
      
   I was expecting that once I have set mynetworks, those networks would   
   allowed to do relaying. Or that IF I need to explicitly set   
   permit_mynetworks, there would be a note to that effect in the area   
   where I set mynetworks. Instead, there is a note pointing to a man page   
   that actually does not contain the needed information.   
      
   And would setting mynetworks to default to the set of networks that   
   are directly attached to the host where postfix is running, be safe   
   enough?   
      
   --   
   Lars Poulsen - an old geek in Santa Barbara, California   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)