First, an apology.  Today Mimecast UK customers have experienced problems with our email services, caused by a network hardware failure at our Woking data centre.  Our infrastructure teams have identified and isolated the problem, and are bringing all affected customer systems back online now.

Customers’ systems will be available soon, but there will be a backlog of email to process, so email may take some time to return to normal.

There are several things you can also do as a customer to make sure your email service is restored as quickly as possible.

  • Firstly check your AdCon addresses for your system availability. Once you can log back into AdCon your email will be flowing too. If you’re not sure of the AdCon address you can click the “Log In” link on our website.
  • Only the even numbered hostname for AdCon will be available for now. They will look something like this. , where ‘serviceNN’ is the cluster number for your account.
  • Importantly, please check your outbound SMTP smarthost connectors on your Exchange server. You should have two configured, one for each host name. Mail will only be delivered to the live host because the other half of the pair will be offline. If you only have one hostname, please make sure you add the second hostname to an outbound SMTP smart host connector.  Please refer to this these KB articles: Exchange 2003, 2007, 2010.
  • MTA2 Customers ONLY: If you’re using MTA2, please check your smart hosts are directed to and
  • Your email will be queued at the sending servers, so you will see email start to flow in and out of your mail server without needing to resend it.

Please note, this is not a full incident report, but an interim update to help you get back online. Our CEO, Peter Bauer, will be posting about the issue later today. But in the meantime, we hope this list of tips helps to resolve the issue as soon as possible.

We would like to take the opportunity to thank you for your patience and we will continue to post updates on our Twitter feed @mimecast

  • sdd

    this is affecting more than just the UK

  • Roger Allen

    Not really very acceptable seeing as you claim 100% uptime. We are still having problems sending and receiving e-mails after 5 hours of this. We now have a multitude of messages stuck in our Mimecast queues due to DNS issues. I think someone should come up with an explanation pretty quick, dont you?

  • Keith Burke

    Being called a Mimecast UK customers and in an Irish company is… insulting.

  • Niall O’Malley

    Hi Roger – apologies for not getting back to you sooner but hopefully you saw the blog posts/Twitter updates. Just in case as you can see from our CEO Peter Bauer’s post ( we’re extremely sorry for the disruption and are committed to learning lessons from the issue. We believe that your service is now back to normal – is there anything else I can help with?

  • Niall O’Malley

    Hi Keith, very sorry for any confusion – we were trying to describe services run out of the UK were affected. We realise that customers worldwide were impacted.

  • Niall O’Malley

    Hello, apologies for any confusion – our aim was to explain the issue affected services ran out of the UK…but we do recognise that it did impact some customers worldwide.

  • AMC Square Services

    This is very effective post.Thanks