Re: postscreen delay inprovement - multple IP addresses
> http://www.postfix.org/POSTSCREEN_README.html#white_veto Noel. I had read that section of the manual but it didn't sink in. Now I get it perfectly. Thanks again, much appreciated. -- View this message in context: http://postfix.1071664.n5.nabble.com/postscreen-delay-inprovement-multple-IP-addresses-tp91174p91224.html Sent from the Postfix Users mailing list archive at Nabble.com.
Re: postscreen delay inprovement - multple IP addresses
On 7/8/2017 2:54 PM, techlist06 wrote: > Will > such a client immediately retry on the next available DNS configured MX (if > available) Yes, many senders will immediately try the secondary MX if the primary gives a temporary error. If you have one MX, most senders will delay some time before a retry. > That > would be great presuming the undesirables don't. > Most clients -- good and bad -- that get a deferral from the primary will try the secondary. Some bad clients will try the secondary first. http://www.postfix.org/POSTSCREEN_README.html#white_veto -- Noel Jones
Re: postscreen delay inprovement - multple IP addresses
re "IP addresses, published in DNS as different IP addresses for the same MX hostname or for different MX hostnames. This avoids mail delivery delays with clients that reconnect immediately from the same IP address. " I understand now this had nothing to do with improving systems that (re)connect from different IPs. Hopefully not too elementary of a question I would like to understand how it helps for clients reconnecting immediately from the same IP. Will such a client immediately retry on the next available DNS configured MX (if available) vs. some other delay to retry on the same IP? As if the primary was considered unavailable so it immediately tries the secondary? That would be great presuming the undesirables don't. Thanks again, Scott -- View this message in context: http://postfix.1071664.n5.nabble.com/postscreen-delay-inprovement-multple-IP-addresses-tp91174p91197.html Sent from the Postfix Users mailing list archive at Nabble.com.
Re: postscreen delay inprovement - multple IP addresses
Thanks guys, I understand now. Much appreciated. -- View this message in context: http://postfix.1071664.n5.nabble.com/postscreen-delay-inprovement-multple-IP-addresses-tp91174p91182.html Sent from the Postfix Users mailing list archive at Nabble.com.
Re: postscreen delay inprovement - multple IP addresses
techlist06: > I'm working on converting to using postscreen. Studying the details. I > have a question from the docs related to the delays due to the effective > greylisting caused by "Tests after the 220 SMTP server greeting". I believe > my server would qualify as a small site receiving mail for just a few > hundred users. > > Snippet from the Howto: > " The following measures may help to avoid email delays: Small sites: > Configure postscreen(8) to listen on multiple IP addresses, published in DNS > as different IP addresses for the same MX hostname or for different MX > hostnames. This avoids mail delivery delays with clients that reconnect > immediately from the same IP address. Note, this recommendation applies to clients that reconnect from the same IP address. > Can someone help me understand why this helps? The postscreen temporary whitelist is by client IP address. > If I add an IP to the server and configure it as a second instance > of the MX hostname, how does that help with a server that may > reconnect from a different IP? Note, the above recommendation applies to clients that reconnect from above recommendation does not apply. > I though tthat if it > reconnected immediately from the same IP, that would be a good thing. Or > maybe I misunderstood "immediately". I took it to mean immediately after > getting a 4xx response and drop. I assume this doesn't do anything to help > with servers like Google that will connect from a different server? Note, the abive recommendation applies to clients that reconnect from the same IP address. If still applies when different servers share the same external (NAT) IP address. Wietse
postscreen delay inprovement - multple IP addresses
I'm working on converting to using postscreen. Studying the details. I have a question from the docs related to the delays due to the effective greylisting caused by "Tests after the 220 SMTP server greeting". I believe my server would qualify as a small site receiving mail for just a few hundred users. Snippet from the Howto: " The following measures may help to avoid email delays: Small sites: Configure postscreen(8) to listen on multiple IP addresses, published in DNS as different IP addresses for the same MX hostname or for different MX hostnames. This avoids mail delivery delays with clients that reconnect immediately from the same IP address. Can someone help me understand why this helps? If I add an IP to the server and configure it as a second instance of the MX hostname, how does that help with a server that may reconnect from a different IP? I though tthat if it reconnected immediately from the same IP, that would be a good thing. Or maybe I misunderstood "immediately". I took it to mean immediately after getting a 4xx response and drop. I assume this doesn't do anything to help with servers like Google that will connect from a different server? Anyway, I'd apprecaite it if someone could elaboate so I understand this detail. Thank you, Scott
