Carlos E. R. wrote:
On 21/09/2018 15.34, Per Jessen wrote:
Carlos E. R. wrote:
On 21/09/2018 02.10, Per Jessen wrote:
Public mail servers, such as those receiving mails for "jessen.ch", "gmx.es", "opensuse.org" etcetera, have a port 25 open, for everyone. They cannot tell who is going to want to transfer some mail to them, they _must_ accept everyone, also a script-kiddie or a hijacked PC behind a Telefonica ADSL line. There is _no_ authentication involved, there is _no_ open relaying involved.
In your case, by Bell blocking _outgoing_ port 25, they are putting a very effective stop to the script-kiddies and the hijacked PCs. As does Bluewin and numerous other Swiss and European providers.
No, not quite. :-)
opensuse.org, for instance, will only accept email which destination is mail list, employers, or whoever holds an @opensuse.org address.
Those are all the same Carlos - "any.thing@opensuse.org". That some are directed to the list server, some forwarded to individual addresses and some fed to the ticketing system is irrelevant seen from the mail server's point of view.
Or maybe others for which this is the handling server. Without authentication.
Right.
But it will refuse to accept an email which destination is carlos@tlefonica.net, because that would be acting as a relay for improper usage.
That is really just another way of saying that the mail server doesn't handle "@tlefonica.net". It might even well receive them, without acting as a relay.
gmx.es will accept without authentication emails for *@gmx.es, but if someone attempts to send to carlos@telefonica.net will ask for authentication; if this fails, the post will be denied.
It is quite simple, actually.
The length of this thread suggests the contrary :-)
The port used has no relevance, the behaviour is basically the same.
It may perhaps be set up like that, but that is not typical. Mail server operators generally use port 25 for mail exchange, and 587/465 for mail submission. As per current standards and conventions. Not all of them, just most. -- Per Jessen, Zürich (22.4°C) http://www.hostsuisse.com/ - virtual servers, made in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org