Further to our Service Alert of March 1st we are again seeing delivery issues to email addresses hosted by Microsoft.

The issue eased over the weekend, but re-appeared yesterday afternoon.

As result some emails to Microsoft recipients are stuck in outbound queues and may take a few hours to be delivered.

We cannot give any idea of how quickly this will be resolved as we have no control over Microsoft policies.

One thing that we believe can be done is for the receiving party, using Microsoft for their email hosting, to do the following:

  • In the Microsoft 365 Defender portal at https://security.microsoft.com, go to Email & Collaboration > Policies & Rules > Threat policies > Anti-spam in the Policies section. To go directly to the Anti-spam policies page, use https://security.microsoft.com/antispam
  • On the Anti-spam policies page, select Connection filter policy (Default) from the list by clicking on the name of the policy.
  • In the policy details flyout that appears, click Edit connection filter policy, then configure the following settings:
  • Always allow messages from the following IP addresses or address range: This setting is the IP Allow list. Click in the box and enter each of our ranges of IP addresses mentioned below, one at a time. Enter a value, and then press Enter or select the complete value that’s displayed below the box.
  • Turn on safe list: Enable the use of the safe list by selecting this check box and enter our network range – – in there.


As much as we hate to have to do this, we’ve put in a ‘hack’ on our new outbound mail servers so that every hour, on the hour, any mails that are in the queues will be moved over to one of the old mail servers for delivery.

Hopefully this will just be a temporary solution until Microsoft fix things their end. What this means is that emails to addresses hosted by Microsoft (e.g. Office365) may be delayed, but if they are, they will still be delivered within an hour of sending.

We will continue to monitor the situation.