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    Blocked ports by Sky?

    This is a discussion on Blocked ports by Sky? within the Sky Broadband help forums, part of the Sky Broadband help and support category; Sorry if I have placed this in the wrong section but since it is not actually about Sky's own E-mail ...

    1. #1
      LA33R's Avatar
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      Question Blocked ports by Sky?

      Sorry if I have placed this in the wrong section but since it is not actually about Sky's own E-mail service, but in stead my own.

      I decided to host my own e-mail server, which has been a little difficult.

      At first I managed to set up the server to work with port 25 / 110 / 143 internally around the house using the Internal IP of the server, but to get it outside the house onto the internet I forwarded these ports on the sky router, which didn't allow people to connect to the server.

      I opened ports 2525 / 2526 / 2527 on the smtp, imap, and pop server, opened them in windows firewall, and forwarded these ports on the router.

      I could then connect using these ports to my server over the internet, but it only seems to have lasted a few hours. Just recently I cannot connect to my server externally any more, but yet only internally. The MX records on the domain are correct, and can send messages to an account hosted on the server from gmail, then recieve these emails on the server later.

      It's a very strange issue which is causing me a large head ache, any help would be grateful.

      Problem is, if i can send email from my gmail address to my own domain and user account on this server, then that means the ports are forwarded correctly, and the server can be contacted. Problem is, using email clients I cannot connect to the server to download my emails...

      so my question is, does sky block ports 25 / 110 / or 143 for security purposes? or should i look into more problems with the server, remembering i can connect to my server internally, so it really cannot be that, it must be something to do with the router or sky's settings.
      Attached Thumbnails Attached Thumbnails Blocked ports by Sky?-capture.jpg  


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    3. #2
      WheelNutWalter's Avatar
      WheelNutWalter is offline Sky User Member
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      Re: Blocked ports by Sky?

      Difficult to trouble shoot fully, unless you also show the definition of those 4 services you've defined in the screenshot?

      Also, with Sky using Dynamic DNS, your email is going to be hit and miss at best for several reasons.

      Receiving:

      1. Whilst you can use Dynamic DNS or a similar service, the DNS entry will carry a low TTL value, many caching DNS servers will ignore the low TTL record set by DynDNS.
      2. MX records should point to an A or AAAA records and must not be a CNAME record (despite some registrars allow you to do this). You can't do what you want without using a CNAME as an MX record, so you are violating email and DNS RFCs, and will likely cause you all sorts of problems. See MX record - Wikipedia, the free encyclopedia

      These two issues above will result in your senders getting lots of 'Temporary Delivery Failure' messages, and they may also see (usually after 5 days), a permanent failure if their own mail server fails to deliver the message. - From your perspective, it could take days before you receive the message, or you may not receive it at all.

      Sending:

      1. You won't be able to use SPF records (for the reasons detailed above), so some mail servers will flag your messages as 'possibly spam'
      2. Many (if not most) mail servers that receive your emails will know that your email has come from a dynamic IP range, and will flag your message as 'almost certainly spam'.

      What you are trying to do is possible, but definitely not advisable, especially if this for production use. If you are using it purely for testing/experimentation, then you'll be okay, if you can live with the problems associated with it.

      If you want to have your own mail server, why not take up a hosting package, or even rent a VPS? These types of systems are designed to reliably do exactly what you are looking for. Alternatively, why not just set up a free Google Apps account on your own domain?

    4. #3
      LA33R's Avatar
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      Re: Blocked ports by Sky?

      Thanks for your reply, looks like I will have to find an alternative to hosting email here. I've added another screen shot of the server just in case you can see anything. Thanks for your help.

      edit: Sorry the image quality screwed up, view here: http://i.imgur.com/XzgzU.jpg

      Blocked ports by Sky?-untitled.jpg

    5. #4
      Isitme's Avatar
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      Re: Blocked ports by Sky?

      I would not be surprised if Sky blocked you, I doubt if they will look kindly on anyone running a mail server, on a domestic broadband service.

      TomD


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