DoH plugin for BIND

Paul Kosinski bind at
Sat May 2 14:39:00 UTC 2020

I wasn't complaining about port 25, I was just citing it as a
counterexample to the claim that ISPs "must" pass all traffic.

I think that most ISPs tell customers how to set up their email clients
(NUAs) including what port to use. Of course it seems that now most
people use Web based email like Gmail, Yahoo (and even Comcast/Xfinity)
so they never see port numbers.

On Sat, 2 May 2020 15:51:58 +0200
Reindl Harald <h.reindl at> wrote:

> Am 02.05.20 um 15:41 schrieb Michael De Roover:
> > In my experience and from what I've heard, very few.   
> if that would be true how comes that most mail clients still default to
> 25 for submission and years after closing port 25 on our mailserver i
> still struggle with customers smartphones still not using 587?
> in fact 10 years ago some ISP's *tried* to kill outbound port 25 because
> there is no point in using it from a homemachine and at that time we
> struggeled also to explain our customers that 25 is plain wrong
> finally they gave up because the damage of open port 25 is killed with
> dnsbl but the customer support went crazy with "why can't i send email
> with my internet connection"
> > Even if your ISP allows it, chances are that other mail servers will reject it  
> that's a completl different story
> > On 5/2/20 3:30 PM, Paul Kosinski via bind-users wrote:  
> >> How many ISPs allow traffic on port 25? My impression is that even many
> >> (non-enterprise) business customers can't use port 25  

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