Jerry 🦙💝🦙Nov 26, 2022
This is really quite fascinating. There is exactly one ISP that is blocking mail from the mail server I run, which is used to deliver mail for infosec.exchange - t-online.de. It annoys me to no end that I see people try to subscribe to infosec.exchange and the confirmation emails are rejected. So, I contacted their postmaster, and to their credit, they got back to me very quickly, but they are basically saying "yeah, you need to use one of the big mail providers if you want to send mail to t-online subscribers".... Ok then. My apologies to any t-online subscribers (who probably can't see this anyhow), but you'll apparently need to use a different email account to register.
Show threadmutaxNov 26, 2022
@jerry that sounds like somebody there misunderstood what you are doing. I got my Mailserver whitelisted there, I think somebody misunderstood non commercial/private as dialup running from home with dynamic IP.
They however usually - at least for Germany
- require some sort of imprint on the website of the domain the MX is running on.
Show threadchexum

@mutax @jerry I think T.O perfectly understands this is a small operator, but their stance is just "use your provider's (ISP, Hosting company) SMTP infrastructure so that we can complain to someone who cares if you send spam".

They completely ignore the fact that as an individual/small business, I'll need to set my SPF up so that any other clients of my ISP can send mail on my behalf. (If the sender cares about SPF but not DKIM).

(cont'd)

Nov 26, 2022 at 4:28pmWeb
Show threadchexumNov 26, 2022

@mutax @jerry generally, if the receiver do not check DKIM, I also have no way of preventing any other of my ISP's customers to NOT send mail via my ISP impersonating my domains.

A stable/unchanging SPF/DKIM setup should mean a reliable sender, IMHO.

A similar issue that many VPS vendors do not allow buying services from users coming via VPNs, or other VPSes(!).

They'd rather see my ephemeral 4G IP than the one VPS exit point I'm using for more than a decade?!? What sense does that make?

Show threadJerry 🦙💝🦙Nov 26, 2022
@chexum @mutax yes - that is it exactly. I't mildly annoying that I would have to pay for a PO Box so that 5 people can subscribe from t-online (or I have to dox myself - not that I'm super hard to find, but still...)
Show threadmutaxNov 26, 2022
@chexum @jerry I am a 'small operator' hosting a handful of domains on two MX and got whitelisted easily with them. I did not mention to them wether I am commercial/non commercial they just wanted to tie the IP address of my VPS at some provider with my postmaster address it seems in their ticket system.