Block specific programs to same address?

[Drezha]

I’m not looking at setting this up (or getting around it), but was just wondering.

The University officially only support Outlook – that’s fine and I’m happy to use it. However, I’ve got an app on the Mac that can link to specific emails – handy for linking to specific emails when making notes. This only works on Mail and Postbox, thanks to Outlook not following RFC conventions.

So Postbox is my mail app of choice on my Mac Mini and it works without issues. However, I’m on campus today, and using my MacBook – I hadn’t set up Postbox, so I’ve tried to open it and it won’t get past the new account screen, as it says it can’t connect. However, I’ve loaded Apple Mail, linked to the same account, and that is able to access the server fine. Likewise, Outlook works as well.

The only thing I can consider is that the autodetect URL is blocked by the University network, as it worked when I set Postbox up when tethered. However, I wasn’t then able to send messages – yet Mail (and Outlook) can.

So I was wondering if individual items could be blocked like that and how it was done – as surely, the emails are being sent via the same server?

"Everything looks interesting until you do it. Then you find it’s just another job" - Terry Pratchett

[Ed P]

I could see HOW to block (look at your Outlook message headers versus that of Postbox). I cannot think WHY they would do it unless you have a SysAdmin who has a particular hatred of things Apple.

Message headers normally contain details of the sender. As the headers seem to follow a standard format it would be a five minute coding job to block Outlook on Apple senders. That does however leave the question of why anyone would do so. :wacko:

On Linux mail headers this is shown as details of the User Agent. Mine says  Mozilla, gives the Linux and Gecko releases and ends with TBird and its version number. I’ve never looked at headers within Outlook but I guess it still uses the User Agent data, for a Mac sender which details the web service, OSX version, Apple Webkit and Safari version numbers.

The following is sheer guesswork on my part.

I suspect that there may be something in your setup that worries your system security. Buy the SysAdmin a beer and ask him/her nicely wtf is happening. Maybe you have a fairly secure system that looks for authorised connections from authorised hardware and throws out anyone else.

Failing all else, and Dave not chipping in, it may have something to do with the Mac OS’s use of bigendian format byte data versus nearly every other OSs use of little endian. If you are sending data maybe something innocent is being flagged as malicious. As you can tell, I really do not know! :unsure:

[Dave Rice]

You can block anything, or part of anything, with the right hardware / software combination on your network. Be that (even part of) a url, port, application, ip address etc.

Level 7 packet analysis needs lots of hardware grunt but we passed that hurdle years ago. DNS blocking can deal with banned urls embedded in others,  like say “http://translate.google.com/translate?tl=it&u=http%3A%2F%2Fwww.bannedsite.com%2F” would fail.

So if it’s been blocked properly you’ll not get around it.

But like Ed, my question would be why block Postbox?

[Drezha]

This is Eduroam, so University wide network across all Unis. However, some do things differently – as at Nottingham I can’t use Steam but I could when at Loughborough (fair play, I was looking at using the JANET network to download my library quickly!)

I just find it a little odd as both Outlook and Apple Mail worked but Postbox didn’t. There is a clause in the T+C’s about not using different mail servers on campus – and in searching that to link here, I think I’ve found the issue.

Following the guide here for Thunderbird shows that I shouldn’t be using the O365 server, but the Nottingham Exchange server. ಠ_ಠ Stupidly, I was aware of the page but hadn’t checked it for Thunderbird!

Must be campus only though as the O365 server works while I’m at home. I’ll change my home settings and see if that works, as then I won’t have to mess about.

"Everything looks interesting until you do it. Then you find it’s just another job" - Terry Pratchett

[Dave Rice]

I can see why they’d do that. Who knows what the Computing students would get up to.

[Drezha]

I’m happy not to use any other SMTP server other than theirs (I access personal email via Roundcube, so that’s not an issue), I just hadn’t expected it for the Universities own email, but I suppose it makes sense. Just odd that Mail and Outlook don’t need to, but I guess that’s perhaps due to the authentication method, as both support OAuth IIRC (to add my Exchange account to macOS and when logging in to Outlook, I was directed to the organisation sign on page).

"Everything looks interesting until you do it. Then you find it’s just another job" - Terry Pratchett

[Ed P]

Interesting that it only barfed for a different server connection. As you say it must have something to do with the authentication method. They obviously fear something that the students will/could do from within the firewall. :wacko:

[Drezha]

Yeah, it’s a possibility. I know that Resilio Sync doesn’t work behind the firewall and annoyingly, I can access SFTP on my Synology via SSH, only if I use Port 22 – any other port out is blocked.

Hey ho!

"Everything looks interesting until you do it. Then you find it’s just another job" - Terry Pratchett

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