← Incidents

DEGRADEDSending delays to Yahoo hosted email addresses.

May 27, 3:45 PM - Jun 1, 9:53 AM, 2021Resolved after 5 daysAffected: API, SMTP (sending)

After an investigation on the sending delays, to Yahoo addresses we could not find a cause for this within Postmark. We then contacted the postmaster at Yahoo/Verizon. They identified a configuration change that was made that caused this. They are rolling back this change.

Incident’s History


We have been seeing consistent delivery rates for Verizon domain for the last 18 hours and are confident that the previous issue causing bounces and delays for some customers is now fully resolved.

Over the past hour we have stopped seeing a high volume of deferrals and delays to Verizon domains. The queues are starting to normalize and delivery rates are improving greatly. We are continuing to monitor the situation very closely.

We are continuing to work directly with Yahoo/Verizon on this ongoing issue. They are responsive to our requests for updates and working to fully resolve the issue causing the delays and deferrals to Yahoo / AOL domains

We are continuing to work with Verizon as they fix the issues causing delays to Yahoo / AOL / Verizon hosted email addresses, and will continue to do so until it's fully resolved.

You may still be experiencing delays to Yahoo/Verizon addresses as Verizon continues to roll back the changes on their end of things.


We can confirm the cause of the delays was not caused by Postmark's infrastructure.

We've worked with the postmasters at Yahoo/Verizon, and have identified the cause of delays. A configuration change at Yahoo hosted domains is being made to resolve this shortly.


We're investigating reports of delayed delivery to Yahoo hosted email addresses (Yahoo, AOL, Verizon) and will provide an update as we know more. Messages are being accepted, and we are attempting delivery to these addresses.