I don't think I'm technically inclined enough to help much further. The most I'd do at that point is look for any flags of some variety but any rejection is likely to be handled by the email provider and not the cell carrier. I don't recall ever receiving a denial or unsent email from the carrier whereas I did get them from the email provider.
Maybe that's how email works? The recipient domain tells the sending domain it was "unable" or unwilling? to comply with the send request and the email server is simply relaying that to you?
I don't know.
I test bugs. I don't diagnose them.
The ones I can point to as being blocked for reasons usually contain URLs that may be considered spam because they're to controversial or unusual websites. It's most definitely from T-Mobile, it even states such. My email gateway here doesn't reject anything because it can't. Postfix has no rules for rejection.
But I'll post a rejection next time I get one, just for technical interest. I don't expect it to be a fixable problem.
Huh weird. Are they any form of European TLD? Such that they'd be governed by the EU's hate speec laws?
Well, the last one I can remember being blocked (and I'm looking for the actual email in the archive, I just had the link handy) was:
A backup server using NSLU2, unslung and rsnapshot - Alien's Wiki https:/= /wiki.alienbase.nl/doku.php?id=3Dlinux:slug
(post is archived)