Thanks Ale and others who replied. Would you all agree that it's not short TTLs per se that are causing issues, but rather, it's some combination of network latency, DNS server performance and (Microsoft's) configuration for how long it will wait for a DNS query to complete?
IOW, if you are doing just one lookup a day (86400), and the average lookup failure rate is say 5%, then you'll have a delivery issue once every 20 days. But with a TTL of 300, you can reasonably expect to have multiple delivery issues every day, given that same 5% error rate. All of this then seems to auger for hosting one's DNS on robust infrastructure behind a low-latency, low-jitter, high-bandwith connection as close as possible to the Internet backbones. Do you agree? Regards, Mark -- _________________________________________________________________ L. Mark Stone, Founder North America's Leading Zimbra VAR/BSP/Training Partner For Companies With Mission-Critical Email Needs Winner of the Zimbra Americas VAR Partner of the Year - Two Years Running ! ----- Original Message ----- | From: "Alessandro Vesely via mailop" <mailop@mailop.org> | To: mailop@mailop.org | Sent: Thursday, August 21, 2025 1:33:50 PM | Subject: Re: [mailop] Consensus Regarding Short TTLs? | On Wed 20/Aug/2025 23:54:03 +0200 Mark Delany via mailop wrote: |> On 20Aug25, Wes Hardaker via mailop apparently wrote: |>> > their short (300) TTLs have no connection to their deliverability issues. |> |>> My associates (and I) have produced a number of academic papers on the |>> subject that show the benefits of a longer TTL value: |>> |>> https://ant.isi.edu/%7ejohnh/PAPERS/Moura18b.pdf |>> https://ant.isi.edu/~johnh/PAPERS/Moura19b.pdf |>> https://datatracker.ietf.org/doc/rfc9199/ |> |> I only skimmed, but do these papers directly address the question of email |> deliveribilty |> and short TTLs? | | | A recent post relating TTL and SPF failure is Steve's | https://www.wordtothewise.com/2025/07/dont-make-your-dns-ttls-too-short/ | | Best | Ale | -- | | | | | | _______________________________________________ | mailop mailing list | mailop@mailop.org | https://list.mailop.org/listinfo/mailop _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
