SMTP (USA) on Opalstack Status

[Resolved] US SMTP was blocked by Microsoft

Mon, 26 Jan 2026 17:09:10 +0000

Our US SMTP service was temporarily blocked by Microsoft due to a spam outbreak from one of our customer accounts. The outbreak has been secured and Microsoft states that the block has been lifted, but that it may take up to 24 hours for the change to take full effect in their systems. (17:09 UTC — Jan 26)

[Resolved] iCloud blocking US and DE SMTP

Thu, 26 Jun 2025 18:46:00 +0000

Fixed - The block was lifted as of 0600 UTC today. (21:19 UTC — Jun 27)

At this time Apple’s iCloud email service is blocking messages sent from our SMTP servers to Apple-hosted domains including icloud.com, me.com, and custom email domains that use the iCloud email service.

We’ve raised a ticket with Apple to determine the cause. (18:46 UTC — Jun 26)

[Resolved] US SMTP blocked by Microsoft

Tue, 01 Oct 2024 20:17:00 +0000

Fixed - Microsoft has lifted the block and their servers are now accepting mail from the US SMTP. (01:47 UTC — Oct 2)

At this time messages sent from the US SMTP server to Microsoft email domains like hotmail.com, live.com, outlook.com, and their international variants are being blocked by Microsoft.

The cause of the block has been identified and corrected and we are now waiting for Microsoft to remove the block.

We’ll update this post as soon as the block has been lifted or when there is other information to report. (20:17 UTC — Oct 1)

[Resolved] Change to default SPF and DMARC policies

Wed, 24 Jan 2024 20:03:12 +0000

On 23 January 2024 we began publishing default SPF and DMARC DNS records for domains that use Opalstack’s DNS and mail systems.

The default policies that we published were somewhat restrictive and were causing mail sent from some customer domains to go to spam so we’ve made the following changes to the policies:

The policy for SPF has been changed from hard fail “-all” to soft fail “~all”.
The policy for DMARC has been changed from “quarantine” to “none”.

The net result of these changes is that customer mail is still compliant with SPF and DMARC but with a less-restrictive policy to help legitimate mail arrive in your inbox. (20:03 UTC — Jan 24)

[Resolved] US SMTP listed on SORBS block list

Fri, 27 Oct 2023 21:32:01 +0000

Fixed - The US SMTP server is no longer listed on the SORBS block list. (22:43 UTC — Oct 30)

Our US SMTP server is currently listed on the SORBS email block list. We’ve already gone through the de-listing process and expect the server to be de-listed in 48 hours or less.

We’ll update this post when we confirm the server is de-listed. (21:32 UTC — Oct 27)

[Resolved] US SMTP and community forum are offline

Wed, 18 Oct 2023 01:23:00 +0000

Fixed - The US SMTP server and community forum are back online. (01:35 UTC — Oct 18)

At this time our US SMTP server (outgoing mail) and our community forum are offline. We’re investigating and will update this post when more information is available. (01:23 UTC — Oct 18)

[Resolved] US SMTP was briefly disrupted

Sun, 07 May 2023 00:37:00 +0000

The US SMTP service was disrupted for approximately 5 minutes during system maintenance. (00:37 UTC — May 7)

[Resolved] US SMTP blocked by Cloudmark

Sat, 27 Aug 2022 02:24:00 +0000

Fixed - We’ve confirmed that there are no further blocks by Cloudmark. (18:32 UTC — Aug 30)

Watching - Cloudmark have stated that they have de-listed the server IPs. We’ll continue to monitor until we see no further blocks in the mail logs. (23:19 UTC — Aug 29)

Watching - We’re still working with Cloudmark to have the US SMTP and MX servers delisted. (20:26 UTC — Aug 29)

Watching - We’ve discovered that the US MX servers are also blocked. This could cause mail forwarding to fail if the final recipient domain is using the Cloudmark block list, so we’ve requested delisting of those as well. (14:27 UTC — Aug 27)

At this time our US SMTP is being blocked by the Cloudmark Sender Intelligence block list. We’ve dealt with the cause and have started the de-listing process.

If you receive a bounce message, please do not attempt to delist the server yourself via the URL in the error message. We’re taking care of it.

We’ll update this post when the server has been removed from the list. (02:24 UTC — Aug 27)

[Resolved] Slow logins on US SMTP

Thu, 18 Aug 2022 21:21:00 +0000

Fixed - The US SMTP server has remained stable following the upgrade and improved configuration. (04:43 UTC — Aug 19)

Watching - We’ve implemented a fix and authentication is working normally at this time. We’ll continue to monitor. (01:49 UTC — Aug 19)

Watching - The original US SMTP is back online. We’ll continue to troubleshoot and monitor. (00:36 UTC — Aug 19)

Identified - We’ve taken the original US SMTP offline for an emergency upgrade. (00:25 UTC — Aug 19)

Watching - The second server is online and is slowly picking up its share of the traffic.

We’ll continue to monitor until we’re satisfied that this issue is resolved. (23:21 UTC — Aug 18)

Identified - We believe the issue is higher-than-average mail traffic, so we’re adding a SMTP server to the pool to take up some of the load. (22:43 UTC — Aug 18)

At this time logins to Opalstack’s US SMTP server are running slowly. Customers may see longer message sending times as a result.

We’re investigating the issue and will update this post when more info is available. (21:21 UTC — Aug 18)

[Resolved] US SMTP was blocked by Microsoft

Fri, 12 Aug 2022 01:13:35 +0000

Our US SMTP service was briefly blocked by Microsoft today. We’ve already corrected the issues which caused the block and mail delivery to Microsoft addresses is working normally at this time. (01:13 UTC — Aug 12)

[Resolved] US SMTP blacklisted

Fri, 13 May 2022 15:56:36 +0000

Fixed - We’ve identified and shut down several websites with insecure contact forms which were sending spam. The site operators have been notified and the US SMTP is no longer blacklisted. (18:59 UTC — May 13)

Our US SMTP service is currently blacklisted. We’re working with the blacklist operators to identify the cause and will have it corrected as soon as possible. (15:56 UTC — May 13)

[Resolved] Mail server certificates expired

Thu, 30 Sep 2021 14:43:09 +0000

Fixed - The issue is now resolved. The root cause was an obsolete root certificate on our servers. The certificate has been updated. (15:10 UTC — Sep 30)

The SSL certificates used by Opalstack’s mail servers are expired. We’re working to correct that at this time and should have it resolved shortly. (14:43 UTC — Sep 30)

[Resolved] US SMTP on Cloudmark blacklist

Sat, 23 Jan 2021 18:43:28 +0000

Fixed - Our US SMTP is no longer on the Cloudmark blacklist. (16:06 UTC — Jan 25)

At this time Opalstack’s US SMTP is on the Cloudmark blacklist. We’re working to have the server delisted and expect that to be done within the next 24-48 hours. (18:43 UTC — Jan 23)

[Resolved] US SMTP blacklisted

Tue, 05 Jan 2021 15:42:00 +0000

Fixed - The US SMTP is no longer blacklisted. (21:59 UTC — Jan 5)

smtp.us.opalstack.com is currently on the Cloudmark blacklist which is used by Comcast and other services. We’ve submitted a delisting request to Cloudmark and are waiting for a followup from them. (15:42 UTC — Jan 5)

[Resolved] US SMTP blocked by outlook.com

Sun, 25 Oct 2020 22:50:00 +0000

Fixed - Microsoft is no longer blocking our US SMTP. (06:08 UTC — Nov 2)

Watching - Microsoft has responded saying that our US SMTP will be removed from the blacklist within the next 24-48 hours. (04:13 UTC — Oct 31)

Identified - Microsoft have responded to our inquiry. It appears that the recent influx of WebFaction customers 🎉 has caused a sudden increase our outgoing mail volume and that this is what triggered the block.

We’ve verified via Microsoft’s own postmaster tools that there have been zero complaints regarding mail from our US SMTP and have provided this data to Microsoft for consideration.

We hope to follow up with a resolution to this issue as soon as possible. Thank you for your patience. (23:49 UTC — Oct 28)

Our US SMTP server smtp.us.opalstack.com is currently on a Microsoft block list used by the following domains and their non-US equivalents:

hotmail.com
live.com
msn.com
outlook.com

We’re working to get the server delisted at this time. (22:50 UTC — Oct 25)

[Resolved] Service disruption in San Francisco

Sun, 16 Aug 2020 13:00:00 +0000

Fixed - All SFO servers are now back online. (16:17 UTC — Aug 16)

Identified - vps15 and mx2.us are back online. (15:54 UTC — Aug 16)

Identified - The webmail server is back online and is operational with the exception of sending mail. We’re still waiting on the remaining servers to come back online. (15:26 UTC — Aug 16)

Identified - The data center team reports:

The issue has been identified as a utility power issue. Power is transferred to generators and is currently running stable and network connectivity is restored for the vast majority of the services.

We’re starting to see the remaining machines come online at this time. (15:08 UTC — Aug 16)

Investigating - opal3.opalstack.com is back online at this time. Other servers are still offline and we’re awaiting a report on the initial investigation from the data center team. (14:19 UTC — Aug 16)

Services in our San Francisco data center are currently disrupted. The following servers are affected:

community.opalstack.com
mx2.us.opalstack.com
opal3.opalstack.com
smtp2.us.opalstack.com
vps4.opalstack.com
vps5.opalstack.com
vps6.opalstack.com
vps13.opalstack.com
vps15.opalstack.com
vps16.opalstack.com
vps17.opalstack.com
vps19.opalstack.com
vps21.opalstack.com
vps24.opalstack.com
vps28.opalstack.com
webmail.us.opalstack.com

We’ll update this post as soon as more information is available. (13:00 UTC — Aug 16)

[Resolved] Cron mail not working

Sun, 14 Jun 2020 22:24:11 +0000

Fixed - Mail from cron jobs should be working normally now. (20:58 UTC — Jun 16)

At the present time mail is not being sent by cron jobs on our web servers. We’re looking into the cause. (22:24 UTC — Jun 14)

[Resolved] US SMTP server blacklisted by Microsoft

Fri, 24 Jan 2020 14:15:00 +0000

Fixed - We’ve verified that Microsoft is now accepting mail from the new US SMTP IP. (16:42 UTC — Apr 7)

Watching - The new US SMTP IP has been live for the past 12+ hours and we are seeing no problems with it.

Additionally, Microsoft has finally responded to state that the original US SMTP IP has been delisted.

We’ll continue to monitor until we’re satisfied that this is resolved. (17:03 UTC — Apr 6)

Identified - Microsoft has continued to be unresponsive to our inquiries, leaving us no recourse except to move our US SMTP to a new IP address.

We will begin the transition on Monday April 6 at 3AM UTC (2020-04-06 03:00 UTC).

We anticipate that this transition will be minimally disruptive (if at all) and will not require any changes to customer mail client settings.

If you notice any problems sending mail during or after the transition, please contact our support team for assistance. (16:45 UTC — Apr 4)

Identified - Microsoft has been unresponsive to our inquiries for the past week so we’ve opened a new ticket with them.

According to Microsoft’s own postmaster tools the US SMTP is not blacklisted and no spam-like activity has been detected since 29 January 2020 - however, we’re still seeing bans for mail sent from the US SMTP to domains that use Office 365 email.

We’ll continue to work with MS to get this resolved. In the meantime, customers affected by this issue can work around it by creating a new mail user on our Frankfurt, Germany mail server and using that user for their SMTP authentication for outgoing mail. (21:28 UTC — Mar 16)

Watching - https://sender.office.com/ is reporting that our SMTP is no longer blocked but we’re still seeing intermittent bans in our mail logs. We’ve reached out to Microsoft for an update and are awaiting their response. (17:29 UTC — Mar 12)

Investigating - This issue is ongoing. We’ll continue to work towards resolution. (16:09 UTC — Feb 27)

Watching - Microsoft has once again assured us that our US SMTP has been removed from their blacklist. We’ll continue to monitor. (17:31 UTC — Feb 12)

Identified - We are still seeing ban activity In spite of the assurance from Microsoft that our US SMTP was removed from their blacklist. We’ll continue to work with them to get this resolved. (15:13 UTC — Feb 6)

Watching - Microsoft has delisted our US SMTP as of approximately 2:15 PM UTC 31 Jan 2020. It may take another couple of hours for the delisting to take full effect, so we will continue to monitor. (15:43 UTC — Jan 31)

Investigating - This issue is ongoing. We’ve taken all of the required actions as dictated by Microsoft so far and are waiting for them to delist the server.

In the meantime if you are a US customer affected by this block, feel free to use our German SMTP server to send mail: smtp.de.opalstack.com (18:32 UTC — Jan 28)

Our US SMTP service is currently on Microsoft’s blacklist. Messages sent to email addresses that use Microsoft’s email services (including hotmail.com and outlook.com) may be bounced back to their original sender.

We’re working with MS to have the server de-listed and will update this incident when it is done. (14:15 UTC — Jan 24)