All systems are operational
Maintenance
US IMAP email server downtime

On 22 July 2026 at 10:00 am US/Central time (UTC -5) one of our US IMAP email servers will be shut down for infrastructure maintenance. The server will be offline during the maintenance and the expected downtime is 6 hours.

Affected customers will be notified individually via email.

No incoming mail will be lost while the server is offline. Mail that arrives during the maintenance will be deferred and delivered once the mail server is back online.

We realize that the timing of this relocation is not ideal. If you have business-critical mailboxes and would like them to be available during the maintenance then please email support@opalstack.com or reply to this message to make arrangements to have your mailboxes migrated to a different IMAP server prior to the scheduled maintenance date.

If you have any questions or concerns regarding this maintenance then please email the Opalstack support team for assistance.

Past Incidents

8th January 2020

Web: Dallas Intermittent outages on opal4

opal4.opalstack.com is experiencing intermittent outages. We're looking into it and will update this item when we have more information.

  • During last week's maintenance our upstream provider updated the server firmware on opal4. We've seen no further issues since that time.

  • The maintenance is complete and Opal4 is back online. We'll continue to monitor.

  • Opal4 is down for the emergency maintenance scheduled earlier today. The total expected downtime is less than one hour.

  • Opal4 will be going down this evening at 9PM US Central (2020-04-01 21:00 UTC-5) for emergency maintenance. The total downtime should be less than one hour.

    The ongoing issue on opal4 has been high system load caused by two separate types of attacks:

    1. High Apache RAM usage due to attacks against common targets like Wordpress sites
    2. High CPU usage by the system firewall under a high volume of SYN packets

    We've resolved the first problem by tuning our application firewall rules and by working with a couple of specific site owners that were receiving the brunt of the attacks.

    The second problem is part of what we're troubleshooting this evening.

    At first glance the SYN packet issue would seem like a common SYN flood attack but other shared servers in our infrastructure receive similar amounts of traffic and don't have any problems mitigating it.

    In the past 24 hours we've discovered key differences in Opal4's hardware compared to the other servers, so we're working with our upstream provider to sort that out.

    Tonight's downtime is at their request to allow them to perform hardware diagnostics in support of that investigation.

  • Opal4 just went through a brief spike in system load during which performance was degraded, but the system is back to normal at this time.

  • We've identified two distinct attack patterns responsible for the intermittent outages on opal4 and are putting measures in place to mitigate them.

  • This intermittent issue on Opal4 has started up again - we will continue to monitor as we work to resolve it.

  • We've seen no further issues in the past several hours.

  • The problem appears to have been caused by temporary high load due to high CPU usage by the system firewall.

    opal4 is stable at this time. We'll continue to monitor.

  • 7th January 2020

    No incidents reported

    6th January 2020

    No incidents reported

    5th January 2020

    No incidents reported

    4th January 2020

    No incidents reported

    3rd January 2020

    No incidents reported

    2nd January 2020

    No incidents reported