Lettermint Outage History

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Lettermint had 31 outages in the last 2 years totaling 55h 17m of downtime — averaging 1.3 incidents per month.

There were 31 Lettermint outages since September 26, 2025 totaling 55h 17m of downtime. Each is summarised below — incident details, duration, and resolution information.

Source: https://status.lettermint.co

Minor July 23, 2026

Intermittent Timeouts Retrieving Inbound Emails and Attachments

Detected by Pingoru
Jul 23, 2026, 02:23 PM UTC
Resolved
Jul 23, 2026, 02:23 PM UTC
Duration
—
Affected: Team API
Timeline · 2 updates
  1. monitoring Jul 23, 2026, 11:19 AM UTC

    Status: Monitoring We are seeing elevated timeouts when accessing object storage due to an ongoing cloud provider outage. Our failover systems are operating as expected, but some requests may still time out. We are monitoring the situation closely. Affected components Team API (Degraded performance)

  2. resolved Jul 23, 2026, 02:23 PM UTC

    Status: Resolved The cloud provider outage has been resolved, and inbound emails and attachments can now be retrieved normally. We have not observed any further timeouts. Affected components Team API (Operational)

Read the full incident report →

Minor July 15, 2026

API availability issues

Detected by Pingoru
Jul 15, 2026, 03:15 PM UTC
Resolved
Jul 15, 2026, 03:15 PM UTC
Duration
—
Affected: Lettermint websiteIncomingTeam APILettermint UISMTP RelaySending APIWebhooks
Timeline · 3 updates
  1. investigating Jul 15, 2026, 03:00 PM UTC

    Status: Investigating We are investigating an increase in 503 Service Unavailable responses. Affected components Lettermint website (Operational) SMTP Relay (Partial outage) Outgoing (Broadcast) (Operational) Lettermint UI (Operational) Sending API (Partial outage) Team API (Partial outage) Outgoing (Transactional) (Operational) Incoming (Partial outage) Webhooks (Operational)

  2. monitoring Jul 15, 2026, 03:01 PM UTC

    Status: Monitoring We experienced a brief period of API unavailability, during which some requests returned 503 Service Unavailable. Multiple API instances temporarily became unresponsive at the same time, leaving insufficient capacity to serve requests. Service has been restored and remains stable. We are monitoring closely and investigating what caused the instances to become unresponsive. Affected components Lettermint website (Operational) Team API (Operational) Outgoing (Transactional) (Operational) Incoming (Operational) SMTP Relay (Operational) Outgoing (Broadcast) (Operational) Webhooks (Operational) Lettermint UI (Operational) Sending API (Operational)

  3. resolved Jul 15, 2026, 03:15 PM UTC

    Status: Resolved API availability has been fully restored and the platform has remained stable. We reverted a health-check configuration that reacted too aggressively to a brief traffic spike, causing healthy instances to be temporarily removed from service. We have confirmed normal operation and are reviewing additional safeguards to prevent a recurrence. Affected components Lettermint UI (Operational) Team API (Operational) Outgoing (Transactional) (Operational) Incoming (Operational) Outgoing (Broadcast) (Operational) Lettermint website (Operational) Sending API (Operational) SMTP Relay (Operational) Webhooks (Operational)

Read the full incident report →

Minor June 27, 2026

Increased error rates on the dashboard and Team API

Detected by Pingoru
Jun 27, 2026, 06:05 PM UTC
Resolved
Jun 27, 2026, 06:05 PM UTC
Duration
—
Affected: Team APILettermint UI
Timeline · 3 updates
  1. investigating Jun 27, 2026, 05:39 PM UTC

    Status: Investigating We are seeing increased error rates on the Lettermint dashboard and our Team API. Requests to the Team API and actions in the dashboard may fail or respond slowly while we look into this. Email delivery is not affected. Transactional and broadcast messages are still being sent and processed as normal. Our team is investigating the cause and we will post an update shortly. Affected components Lettermint UI (Degraded performance) Team API (Degraded performance)

  2. monitoring Jun 27, 2026, 06:01 PM UTC

    Status: Monitoring We are no longer seeing elevated error rates on the Team API or dashboard and functionality appears to have returned to normal. We are continuing to monitor the situation closely to ensure stability, but no new errors have been observed since mitigation was applied. Affected components Lettermint UI (Operational) Team API (Operational)

  3. resolved Jun 27, 2026, 06:05 PM UTC

    Status: Resolved This incident has been resolved. We applied a fix and have confirmed that the dashboard and Team API are working normally, with no further errors. Affected components Lettermint UI (Operational) Team API (Operational)

Read the full incident report →

Minor June 26, 2026

Elevated 500 errors with API authentication

Detected by Pingoru
Jun 26, 2026, 09:01 PM UTC
Resolved
Jun 26, 2026, 09:01 PM UTC
Duration
—
Affected: Lettermint websiteIncomingTeam APILettermint UISMTP RelaySending APIWebhooks
Timeline · 2 updates
  1. investigating Jun 26, 2026, 08:56 PM UTC

    Status: Investigating We are investigating an increase in 500 errors. Affected components Lettermint website (Operational) Sending API (Partial outage) Team API (Partial outage) Outgoing (Transactional) (Operational) Outgoing (Broadcast) (Operational) Webhooks (Operational) Lettermint UI (Operational) Incoming (Operational) SMTP Relay (Partial outage)

  2. resolved Jun 26, 2026, 09:01 PM UTC

    Status: Resolved We have resolved the API token authentication issue as of 23:01 CEST by rolling back the change that introduced the failure. Between approximately 22:56 and 23:01 CEST, a subset of API requests using tokens may have failed when they required a fresh authentication lookup. Requests using already-cached token authentication continued to work. We are treating this as a high-priority reliability incident. Given the recent increase in production incidents, we are pausing this rollout path and tightening our migration and deployment safeguards before reintroducing the change. All affected services are currently operating normally. Affected components Lettermint website (Operational) Team API (Operational) SMTP Relay (Operational) Outgoing (Broadcast) (Operational) Webhooks (Operational) Lettermint UI (Operational) Sending API (Operational) Outgoing (Transactional) (Operational) Incoming (Operational)

Read the full incident report →

Minor June 23, 2026

[Ratelimit] Delayed sending to Outlook OLC

Detected by Pingoru
Jun 23, 2026, 04:24 PM UTC
Resolved
Jun 23, 2026, 04:24 PM UTC
Duration
—
Timeline · 3 updates
  1. identified Jun 23, 2026, 08:39 AM UTC

    Status: Identified We are actively mitigating this issue. You might see deferrals in your webhooks or UI instead of delayed processing. Please note emails are still being retried. This is caused by an increase in volume due to the ongoing incident with Spamhaus listing, which is being resolved and the delisting is being propagated. This issue does not impact Microsoft 365 (Outlook 365) addresses nor other providers. Broadcast is also not affected by the issue. Our sincere apologies for the inconvenience.

  2. monitoring Jun 23, 2026, 08:40 AM UTC

    Status: Monitoring We are still actively working on this issue. An update from Spamhaus was received ~20 minutes ago and delisting is being propagated worldwide. We will keep monitoring the situation. Our sincere apologies for the inconvenience.

  3. resolved Jun 23, 2026, 04:24 PM UTC

    Status: Resolved We are not seeing anymore deferrals related to ratelimit for these IPs and will mark it as resolved. Apologies for the inconvenience this has caused.

Read the full incident report →

Minor June 23, 2026

[Blocklist] Transactional IP listed in Spamhaus

Detected by Pingoru
Jun 23, 2026, 04:24 PM UTC
Resolved
Jun 23, 2026, 04:24 PM UTC
Duration
—
Timeline · 6 updates
  1. identified Jun 23, 2026, 06:01 AM UTC

    Status: Identified We’ve identified that three of our outbound transactional IP addresses have been blocklisted, affecting email delivery for some customers. The team is currently investigating the cause and working on delisting the IP. In the meantime, the IP address has been suspended and will not be used until the issue is resolved. This does not affect other IPs in the pool nor broadcast routes. If you have seen a hard bounce because of this, you can safely reactivate the recipient from your suppression management.

  2. identified Jun 23, 2026, 08:41 AM UTC

    Status: Identified We are still actively working on this issue. An update from Spamhaus was received ~20 minutes ago and delisting is being propagated worldwide. We will keep monitoring the situation. Our sincere apologies for the inconvenience.

  3. identified Jun 23, 2026, 10:47 AM UTC

    Status: Identified We are still actively working on this issue and are awaiting an update from Spamhaus. We will keep monitoring the situation. Our sincere apologies for the inconvenience.

  4. identified Jun 23, 2026, 01:38 PM UTC

    Status: Identified We are still actively working on this issue and are awaiting an update from Spamhaus. We will keep monitoring the situation. Our sincere apologies for the inconvenience.

  5. monitoring Jun 23, 2026, 03:14 PM UTC

    Status: Monitoring We’ve been in contact with Spamhaus and the delisting process has now been successfully applied. The delisting has been put into effect, but mail providers that rely on Spamhaus may take some time to refresh and propagate these changes within their own systems and internal caches. We are currently monitoring the situation closely while these updates continue to propagate. Once we determine that delivery has stabilized and it is safe to proceed, we will begin retrying affected emails that were not yet successfully delivered and provide further updates as needed.

  6. resolved Jun 23, 2026, 04:24 PM UTC

    Status: Resolved We are not seeing anymore bounces related to the Spamhaus listing and are working on resending all impacted messages. Due to the length and impact of this incident we will share a post-mortem on this incident. Apologies for the inconvenience this has caused.

Read the full incident report →

Minor June 22, 2026

[Blocklist] Transactional IP is listed in Spamhaus

Detected by Pingoru
Jun 22, 2026, 01:07 PM UTC
Resolved
Jun 22, 2026, 01:07 PM UTC
Duration
—
Timeline · 2 updates
  1. monitoring Jun 22, 2026, 12:32 PM UTC

    Status: Monitoring We’ve identified that one of our outbound transactional IP addresses has been blocklisted, affecting email delivery for some customers. The team is currently investigating the cause and working on delisting the IP. In the meantime, the IP address has been suspended and will not be used until the issue is resolved. This does not affect other IPs in the pool nor broadcast routes. If you have seen a hard bounce because of this you can safely reactivate the recipient from your suppression management. As of 11.44 UTC, the listing has been removed and we are monitoring the situation. Affected components Outgoing (Transactional) (Degraded performance)

  2. resolved Jun 22, 2026, 01:07 PM UTC

    Status: Resolved We have not seen any new bounces due to the listing and are actively looking into resending all bounced messages. Recipients that bounced due to the Spamhaus listing should not be suppressed. If it still did so, feel free to remove these from the suppression list. Our sincere apologies for the inconvenience. Affected components Outgoing (Transactional) (Operational)

Read the full incident report →

Minor June 17, 2026

Email submissions not being processed

Detected by Pingoru
Jun 17, 2026, 08:18 PM UTC
Resolved
Jun 17, 2026, 08:18 PM UTC
Duration
—
Affected: IncomingSMTP Relay
Timeline · 5 updates
  1. investigating Jun 17, 2026, 05:00 PM UTC

    Status: Investigating We are currently investigating reports of email submitted via the SMTP relay not being processed. Affected components SMTP Relay (Full outage) Incoming (Full outage)

  2. identified Jun 17, 2026, 05:52 PM UTC

    Status: Identified We have identified the issue and our team is working on a fix. We'll keep you posted. Apologies for the inconvenience. Affected components Incoming (Full outage) SMTP Relay (Full outage)

  3. monitoring Jun 17, 2026, 06:06 PM UTC

    Status: Monitoring A fix is being deployed and we'll be monitoring the situation. Affected components Incoming (Full outage) SMTP Relay (Full outage)

  4. monitoring Jun 17, 2026, 06:09 PM UTC

    Status: Monitoring We are seeing improvements and services are back to normal. In the meantime, we will keep monitoring the situation closely and apologies for the inconvenience this has caused. A public post-mortem will also be shared. Affected components Incoming (Operational) SMTP Relay (Operational)

  5. resolved Jun 17, 2026, 08:18 PM UTC

    Status: Resolved We have continued monitoring and have not observed any further recurrence of this issue. The incident is now resolved. We have completed a post-mortem and will publish it shortly with more detail on the impact, root cause, and follow-up actions. Affected components SMTP Relay (Operational) Incoming (Operational)

Read the full incident report →

Minor May 29, 2026

Delay in sending emails

Detected by Pingoru
May 29, 2026, 01:20 PM UTC
Resolved
May 29, 2026, 01:20 PM UTC
Duration
—
Timeline · 4 updates
  1. investigating May 29, 2026, 10:59 AM UTC

    Status: Investigating We are currently investigating a sudden increase in queue times for emails. Emails are delayed for ~2 minutes on average. We will keep you posted. Affected components Outgoing (Transactional) (Degraded performance) Outgoing (Broadcast) (Degraded performance)

  2. identified May 29, 2026, 11:09 AM UTC

    Status: Identified We have identified the issue causing a delay in processing of emails and are working on a fix. Currently emails are in queue for an average of ~22 seconds, higher than the usual average of a couple milliseconds. We will keep you posted once a fix has been implemented. Affected components Outgoing (Transactional) (Degraded performance) Outgoing (Broadcast) (Degraded performance)

  3. monitoring May 29, 2026, 12:00 PM UTC

    Status: Monitoring A fix has been implemented and we're monitoring the situation. Queues are being processed quickly again and the time-to-inbox dropped to sub-10 seconds as expected. Apologies for the inconvenience this caused. Affected components Outgoing (Transactional) (Operational) Outgoing (Broadcast) (Operational)

  4. resolved May 29, 2026, 01:20 PM UTC

    Status: Resolved We have not seen any regressions related to emails being queued for longer than expected. Therefore we're marking this incident as resolved. If you still notice any issues, do reach out to support. Affected components Outgoing (Transactional) (Operational) Outgoing (Broadcast) (Operational)

Read the full incident report →

Minor April 7, 2026

Time-outs with larger emails

Detected by Pingoru
Apr 07, 2026, 08:31 PM UTC
Resolved
Apr 07, 2026, 08:31 PM UTC
Duration
—
Affected: SMTP Relay
Timeline · 3 updates
  1. investigating Apr 07, 2026, 06:43 PM UTC

    Status: Investigating We are noticing degraded performance with sending larger attachment to our SMTP relay and are currently investigating the issue. Affected components SMTP Relay (Degraded performance)

  2. monitoring Apr 07, 2026, 07:52 PM UTC

    Status: Monitoring Fix has been deployed for the intermittent connection errors affecting SMTP submissions with larger attachments. We are now observing traffic to confirm the issue is fully resolved. No action is required from customers. Affected components SMTP Relay (Operational)

  3. resolved Apr 07, 2026, 08:31 PM UTC

    Status: Resolved We are no longer seeing any connection issues. A post-mortem will be shared as soon as possible. Our findings have been shared with the developer of the package and will cooperate to fix the issue for the ecosystem. Affected components SMTP Relay (Operational)

Read the full incident report →

Minor March 27, 2026

Email sending API degraded

Detected by Pingoru
Mar 27, 2026, 06:53 PM UTC
Resolved
Mar 27, 2026, 06:53 PM UTC
Duration
—
Affected: Sending API
Timeline · 3 updates
  1. identified Mar 27, 2026, 06:24 PM UTC

    Status: Identified We have identified the issue with our email sending API and are working on a fix. SMTP is not affected. We will provide updates as soon as we have more information. Affected components Sending API (Partial outage)

  2. monitoring Mar 27, 2026, 06:32 PM UTC

    Status: Monitoring We have deployed a fix for the issues with our email sending API. We are no longer seeing errors and will continue to monitor. Affected components Sending API (Operational)

  3. resolved Mar 27, 2026, 06:53 PM UTC

    Status: Resolved This incident is resolved. Our email sending API is fully operational and we are no longer seeing any errors or alerts. Affected components Sending API (Operational)

Read the full incident report →

Minor March 25, 2026

Intermittent delay in delivery

Detected by Pingoru
Mar 25, 2026, 08:56 AM UTC
Resolved
Mar 25, 2026, 08:56 AM UTC
Duration
—
Timeline · 3 updates
  1. investigating Mar 25, 2026, 07:36 AM UTC

    Status: Investigating We are observing an increased amount of softbounces due to issues related to networking and are currently investigating. Only a small percentage of traffic is impacted and will be retried in minutes. Affected components Outgoing (Transactional) (Degraded performance) Outgoing (Broadcast) (Degraded performance)

  2. monitoring Mar 25, 2026, 08:28 AM UTC

    Status: Monitoring The root cause has been identified and a fix has been implemented. We will keep monitoring the results, all emails are now being forced to retry immediately. Affected components Outgoing (Transactional) (Operational) Outgoing (Broadcast) (Operational)

  3. resolved Mar 25, 2026, 08:56 AM UTC

    Status: Resolved We are no longer seeing any issues and are marking this incident as resolved. We apologise for the inconvenience this may have caused. Affected components Outgoing (Transactional) (Operational) Outgoing (Broadcast) (Operational)

Read the full incident report →

Minor March 5, 2026

Intermittent increased latency and error rate

Detected by Pingoru
Mar 05, 2026, 11:11 AM UTC
Resolved
Mar 05, 2026, 11:11 AM UTC
Duration
—
Affected: Lettermint websiteIncomingTeam APILettermint UISMTP RelaySending API
Timeline · 5 updates
  1. investigating Mar 05, 2026, 09:26 AM UTC

    Status: Investigating We are investigating possible issues related to accessing Lettermint services. Updates will be shared as soon as we know more. Affected components Sending API (Partial outage) Team API (Partial outage) Incoming (Partial outage) SMTP Relay (Partial outage)

  2. monitoring Mar 05, 2026, 09:40 AM UTC

    Status: Monitoring We are monitoring the situation following an infrastructure node failure in one of our availability zones. Read database queries experienced degradation for approximately 72 seconds between 09:21–09:23 UTC impacting authentication during email submission and other endpoints. Write operations and cache services were unaffected throughout. All services have fully recovered. Affected components SMTP Relay (Operational) Sending API (Operational) Team API (Operational) Incoming (Operational)

  3. identified Mar 05, 2026, 10:07 AM UTC

    Status: Identified We have received an update to the cause of this incident, which is in fact not related to a node hardware failure as previously thought. Our cloud provider has accidentally triggered a rolling replacement of all cluster nodes in our EU-West region. This process is ongoing and may cause intermittent latency spikes or brief errors as workloads migrate and failover between nodes. Impact should be minimal. Our team is in contact with our cloud provider to receive updates on the resolution. We will provide updates as the situation develops. Affected components Lettermint UI (Degraded performance) Lettermint website (Degraded performance) Sending API (Degraded performance) Team API (Degraded performance) Incoming (Degraded performance) SMTP Relay (Degraded performance)

  4. monitoring Mar 05, 2026, 10:22 AM UTC

    Status: Monitoring Our cloud provider confirmed the roll-out was stopped. We are also no longer observing any more nodes being replaced for the last 30 minutes. All services are healthy again and we will keep monitoring the situation. Affected components Lettermint UI (Operational) Lettermint website (Operational) Sending API (Operational) Team API (Operational) Incoming (Operational) SMTP Relay (Operational)

  5. resolved Mar 05, 2026, 11:11 AM UTC

    Status: Resolved No more regressions have been noticed and all services are still healthy. Incident has been resolved. A follow-up from our cloud provider is still expected and we are taking measures to prevent issues like this in the long-term. Affected components SMTP Relay (Operational) Lettermint UI (Operational) Lettermint website (Operational) Sending API (Operational) Team API (Operational) Incoming (Operational)

Read the full incident report →

Minor February 18, 2026

[Ratelimit] Broadcast IP is rate-limited with Outlook (OLC)

Detected by Pingoru
Feb 18, 2026, 01:08 AM UTC
Resolved
Feb 18, 2026, 01:08 AM UTC
Duration
—
Timeline · 3 updates
  1. identified Feb 17, 2026, 03:24 PM UTC

    Status: Identified We've identified that two of our outbound broadcast IP addresses have been ratelimited, affecting email delivery for some customers. The team is currently investigating the cause and working on delisting the IPs. In the meantime, the IP addresses has been suspended and will not be used until the issue is resolved. This does not affect other IPs in the pool nor transactional routes. These rate limits cause soft-bounces. We will keep retrying to send the emails. Affected components Outgoing (Broadcast) (Degraded performance)

  2. monitoring Feb 17, 2026, 04:26 PM UTC

    Status: Monitoring We're no longer seeing any bounces, but we'll keep monitoring it. Affected components Outgoing (Broadcast) (Operational)

  3. resolved Feb 18, 2026, 01:08 AM UTC

    Status: Resolved We are no longer seeing any deferrals related to these IP addresses and emails are sent out accordingly. Affected components Outgoing (Broadcast) (Operational)

Read the full incident report →

Minor February 13, 2026

[Blocklist] Intermittent mailblocks to iCloud addresses

Detected by Pingoru
Feb 13, 2026, 05:27 PM UTC
Resolved
Feb 13, 2026, 05:27 PM UTC
Duration
—
Timeline · 2 updates
  1. investigating Feb 13, 2026, 03:20 PM UTC

    Status: Investigating We've been notified of intermittent delivery failures due to hard bounces to iCloud, affecting email delivery for some customers. The team is currently investigating the cause and working on resolving this issue. If you have seen a hard bounce because of this you can safely reactivate the recipient from your suppression management.

  2. resolved Feb 13, 2026, 05:27 PM UTC

    Status: Resolved We see improvements and no more bounces related to the block. After further investigation, iCloud was having issues where it was incorrectly rejecting mail with IP block responses while it was not the case. This has been confirmed with others. We will keep monitoring the situation closely.

Read the full incident report →

Minor February 5, 2026

Service Disruption

Detected by Pingoru
Feb 05, 2026, 01:48 PM UTC
Resolved
Feb 05, 2026, 01:48 PM UTC
Duration
—
Affected: IncomingTeam APISMTP RelaySending API
Timeline · 3 updates
  1. identified Feb 05, 2026, 11:20 AM UTC

    Status: Identified At approximately 12:20 PM (CET), we started receiving reports of infrastructure issues affecting our services. This is currently causing database connectivity problems, which may result in failed API requests or delays in email processing. Our team is actively investigating the issue. We will provide updates as soon as more information is available. Affected components Sending API (Partial outage) Team API (Partial outage) Outgoing (Transactional) (Partial outage) Incoming (Partial outage) SMTP Relay (Partial outage) Outgoing (Broadcast) (Partial outage)

  2. monitoring Feb 05, 2026, 12:53 PM UTC

    Status: Monitoring Our services have been restored and we are no longer seeing any issues. We are closely monitoring our infrastructure to ensure everything remains stable. Once this incident is fully resolved, we will publish a post-mortem with a detailed overview of what happened and what steps we are taking to prevent this in the future. Affected components Sending API (Operational) Team API (Operational) Outgoing (Transactional) (Operational) Incoming (Operational) SMTP Relay (Operational) Outgoing (Broadcast) (Operational)

  3. resolved Feb 05, 2026, 01:48 PM UTC

    Status: Resolved We have confirmed everything is stable again and are working with our upstream provider to work out the final details. As part of our post-incident process we are working on resolving any individual issues that might still have occurred. Do reach out to support if you have any questions. Our sincere apologies for the inconvenience. A post-mortem will be shared as soon as possible. Affected components SMTP Relay (Operational) Outgoing (Broadcast) (Operational) Sending API (Operational) Team API (Operational) Outgoing (Transactional) (Operational) Incoming (Operational)

Read the full incident report →