API update: deprecating /bounces/tags

The /bounces/tags endpoint is used to return all tags from bounced messages as a string array. This endpoint gets extremely low utilization, so we are deprecating it on December 2nd, 2019. We are reaching out to the few customers who use this endpoint directly to help them transition.

If you do have a need to filter bounces by a specific tag, a better approach is to use the /bounces endpoint with filtering, as outlined in our docs here.

If you have any questions about this, please contact our support team.

API update: Modular Webhook management

Back in March 2018 we released modular webhooks, allowing you to choose which events you’d like to send to each specified hook URL. Up to now this has only been possible through the UI. We’re happy to announce that we just released a brand new /webhooks API endpoint, which brings support for the setup and maintenance of modular webhooks, as well as some of the Message Stream functionality we’ve been working on.

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The new endpoint lets you list all existing webhook configurations; retrieve a specific configuration; and of course create, update, and delete modular webhook configurations.

Note that at this point we haven’t made any changes to how our /server and /servers endpoints work with regard to webhooks. Setting/updating webhooks via that endpoint will continue to set a single hook for your default transactional stream. We plan to update this in the future, but we’ll give you plenty of advance notice when that happens.

For details on how to use the new /webhooks endpoint, head over to our docs. And if you have any questions, please let us know!

October, 2019

Security upgrades to SMTP sending — action may be required

We wanted to let you know about a few changes we’re making to SMTP sending in the coming weeks to make this endpoint more secure. These changes will only affect sending via SMTP. If you use only the Postmark REST API to send, no further action is required on your part.

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What’s changing

The following changes will be made to our supported SMTP TLS configuration:

  • Deprecation and removal of TLSv1 support.
  • Deprecation and removal of several older and less secure cipher suites.
  • Modification of cipher parameters to require larger key sizes.

We understand that this type of change can be disruptive, so we want to provide you with ample time to test and verify that your application will be able to continue sending mail using the updated security settings.

These are the key dates for these changes:

  • October 29th, 2019 (today): Deprecation announcement, and testing endpoints are made available.
  • December 9th, 2019: “Blackout testing”. We will temporarily move SMTP traffic to the updated configuration for a few hours throughout the day so that customers that have not seen this notice are alerted to issues before the final cutover.
  • December 14th, 2019: All production traffic will be moved to the updated security configuration.

The most significant change, which might affect you, is that we are disabling TLSv1 on December 14, 2019. This protocol is old and vulnerable, so we will be rejecting connection requests that use TLSv1.

What you need to do

Before the cutover date on December 14th, 2019, we recommend that you perform some tests against the following temporary testing endpoint: future-smtp.postmarkapp.com. This endpoint matches the changes we’ll be making, so if everything works as expected, you’re good to go. Just switch back to using smtp.postmarkapp.com and no further action will be needed.

If you run into any issues using the temporary endpoint (i.e., your SMTP client is unable to connect), please contact our support team and let us know what OS and SMTP client you’re using to connect. We may be able to provide specific instructions for using newer TLS configurations.

Once again, we are going to disable TLSv1 on December 14, 2019. Please perform all testing and make any necessary code changes before this date.

Please let us know if you have any questions about these changes.

September, 2019

We are ending support for the Tags Triggers API on October 14th, 2019

A small number of customers use our Tags triggers API to track open events on emails sent with specific tags. We’re working on some more powerful features in our other API endpoints, so we are ending support for this feature, and it will be disabled on October 14th, 2019. We ask that customers who currently use this API to track opens based on tags update their applications to instead enable open tracking on a Message Stream level, or for individual messages.

Please let us know if you have any questions about this, or if we can help in any way to make the transition to stream- or message-level tracking.

Additional SMTP Endpoint IPs Added

We have added the following IPs to our SMTP endpoint service. If you send email using SMTP and explicitly whitelist our SMTP endpoint IPs, these will need to be added:

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  • 3.208.98.158
  • 3.93.205.235
  • 3.95.122.1
  • 13.209.189.43
  • 15.164.159.110
  • 52.208.94.138
  • 52.210.34.36
  • 54.77.222.65

May, 2019

API Bug Fix May 23, 2019

Important changes to the way we handle headers when sending with SMTP

On Monday, May 20th we made a change to the way we process SMTP headers for emails that are sent with SMTP. Please note that this change does not affect sending via the API.

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Historically, when Postmark accepted messages over SMTP, we have constructed the To, Cc, and Bcc headers for messages sent to show only the subset of recipients you specify during sending. In some uncommon cases, this behavior meant that not all recipients would be visible in the message that is delivered to your recipients.

With this update, we will ensure that the recipients that are visible in your messages’ To and Cc headers are the same as what will be shown to the final recipients of your messages. We will no longer reconstruct them based on our older behavior, which, in some uncommon cases, could have prevented some recipients from being displayed in the final email that we deliver.

Read the blog post for full details.

February, 2019

Starting March 7th our SMTP outbound servers will only support encrypted connections using TLS

We will disable support for SSL v3 on March 7th, and going forward our servers will only support encrypted SMTP connections using TLS (1.0 - 1.3). Most customers will not be affected by this change. However, you can double check that your SMTP client is compatible by temporarily sending mail through future-smtp.postmarkapp.com instead of smtp.postmarkapp.com.

future-smtp.postmarkapp.com points to the new servers (and new IPs) and it does not allow SSL v3 connections. If you use connection to test and everything works well, no further action is needed and sending should continue through our current endpoint: smtp.postmarkapp.com.

If you are having trouble connecting over future-smtp.postmarkapp.com you will need to update your SMTP client. Please can let us know if you are not able to resolve or update your SMTP client before the switchover date.

July, 2018

Version 2.6.0 of the official PHP library for Postmark

This release includes support for our new metadata feature. You may now include metadata with your outbound messages, and Postmark will include that data in webhook payloads, message details, and message searches. See the full release announcement here.

This release also enables you to specify the BaseURL for each API request, making testing with Guzzle a lot easier.

Finally, you can now enable, or disable SMTP API Error Webhooks for Servers using the Admin Client.

As always, we hope this release helps you get even more value from Postmark, and please feel free to contact us if you have any questions or requests!

Updates to the Swiftmailer Transport for Postmark

Our Swiftmailer Transport for Postmark has been updated with some minor enhancements, and it also now works with SwiftMailer 6.

Postmark official .net client updated to v3.3.0

This release of the official .net client for Postmark includes the addition of the Domains APIs, support for our new custom metadata feature, as well as the “EnableSMTPErrorHook” property to the the Create and Edit Server endpoint methods.

Custom metadata for your emails

You can now add custom metadata to your emails, and we'll pass that same data back to your system through our webhooks.

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For more details on how to implement and use this feature, check out the announcement blog post, help documentation as well as our updated developer documentation.

March, 2018

Modular webhooks

You can now add multiple webhook URLs for a server and choose which events you’d like to send to each specified URL.

December, 2016

Webhook for delivery events

Postmark can now notify your application of delivery events via webhooks so you can do a variety of things like feed delivery events into an internal system, provide delivery even notifications to your customers, or aggregate delivery even data to see patterns and respond accordingly.