We noted that a few of our UK customers still have some inbound traffic directed through the North American infrastructure, rather than the European infrastructure, due to DNS entries on our side that have not been updated. In order for this traffic to route through the European infrastructure, we will be updating the relevant DNS entries on Monday, October 7.
This update will mean that delivery of inbound mail for this subset of UK customers will be coming from different IP addresses than at present – specifically from the 18.104.22.168 / 255.255.255.0 network. These IP addresses have been communicated multiple times through multiple channels (including a notice that has been on the home page of the control panel for many months) but we are posting this note to the status site as an additional precaution.
If customers experience any inbound delivery issues (specifically, messages being queued) on or after Monday, the likely culprit is that are limiting inbound SMTP traffic to selected IP addresses, and they have not correctly updated their firewall and/or mail server configuration to accept inbound SMTP traffic from this network. Customers who configure their firewall to limit inbound SMTP traffic are encouraged to verify that such traffic is allowed from all of our IP addresses, which can be referenced from the home page of the control panel.
Thanks for your attention.