Super Hub Port Blocking Woes


April 26, 2022

email router server


When setting up my own email server, I was fortunate to find that Virgin Media were not restricting port 25 – the default SMTP port.

This did come as somewhat of a surprise. It’s common practice among ISPs to block this port on residential networks. But VM had this port freely available for customers to open.

Well, that was the case, with the old Super Hub 2.

Today, I got a free upgrade to the new Super Hub 5. Along with assigning my network a new IP address (causing a brief scramble to update various domain DNS records), I found a nice surprise while setting up port filtering rules on the new hub.

Restricted port message
SMTP port 25 is restricted.

It’s not blocked at network level – it’s reserved on the hub itself. Giveth with one hand, taketh away with the other.

Looks like I’ll be switching over to port 587 instead, which fortunately, isn’t blocked by the hub. To be fair, this is generally considered best practice these days, despite port 25 still seeing widespread use.

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