---
title: The Winter 2025 Release
description: The winter 2025 release is here, and it is even bigger than the last one!
---

[KumoMTA Blog](https://kumomta.com/blog)

# [The Winter 2025 Release](https://kumomta.com/blog/winter-2025-release)

 Written by [Tom Mairs](https://kumomta.com/blog/author/tom-mairs) | Dec 3, 2025, 2:00:41 PM

The Fall release of [KumoMTA](https://kumomta.com/) was only six weeks ago and was one of the largest, with more than 20 enhancements.  That sounds like a lot, right?  Hold my beer.

Yesterday, we dropped [the 2025 Winter release](https://docs.kumomta.com/changelog/2025.12.02-67ee9e96/) with more than forty (yes, 40!) enhancements and upgrades, including some powerful tools for inter-node [message transfer](https://docs.kumomta.com/reference/kcli/xfer/), which has been a request from some of our larger [Gold Sponsor](https://kumomta.com/support) customers.  Another highly requested change is the inclusion of [time handling with nanosecond granularity](https://docs.kumomta.com/reference/kumo.time/Time/), along with a special “[TimeDelta](https://docs.kumomta.com/reference/kumo.time/TimeDelta/)” object that allows for handling of “durations” in code.

For the "[Blue team](https://en.wikipedia.org/wiki/Blue_team_(computer_security))" security crowd, we have added a number of enhancements to empower email security teams.  If you have a process that deconstructs a message into [mime\_parts](https://docs.kumomta.com/reference/message/parse_mime/), you can then examine any attachments to determine the [filetype](https://docs.kumomta.com/reference/kumo.file_type/from_bytes/) and handle it appropriately. You can dig into the message DNS with new [ptr\_host](https://docs.kumomta.com/reference/kumo.dns/ptr_host/), [reverse\_ip](https://docs.kumomta.com/reference/kumo.dns/reverse_ip/), and [rbl\_lookup](https://docs.kumomta.com/reference/kumo.dns/rbl_lookup/) functions. You can verify the message [ARC](https://docs.kumomta.com/reference/message/arc_verify/) and [seal](https://docs.kumomta.com/reference/message/arc_seal/), as well as the previously released dkim\_verify. But my favourite new security addition has to be the [mail\_auth.check](https://docs.kumomta.com/reference/policy-extras.mail_auth/check/) function. This is like a Swiss Army Knife for message authentication, returning DKIM, SPF, SMTP\_Auth, DMARC, and ARC data all in a single call. Seriously, can you get any better - or easier - than this?

local check\_result = mail\_auth.check(msg)

While we are on security, let's talk about the new crypto module.  Thanks to [@dariomaiocchi](https://github.com/dariomaiocchi) for the initial PR#395 to add [AES 128/256 encrypt and decrypt functions](https://docs.kumomta.com/reference/kumo.crypto/aes_encrypt_block/) to the project.  This opens many options for handling encrypted data.  Another interesting crypto addition came from the need to use AWS V4 signatures when passing data to AWS tools as an IAM user.  Thanks to [@AdityaAudi](https://github.com/AdityaAudi?_gl=1*1cvcs13*_gcl_au*NjAxMzEzODIyLjE3NjQ1NTc4MTY.*_ga*MTU3NDI1OTAxNC4xNzU2NTA3NDM1*_ga_LNBCW1KF8J*czE3NjQ2OTk3OTAkbzIxMCRnMSR0MTc2NDcwNDAxMyRqMjckbDAkaDA.) for PR#457 that led to adding the [aws\_sign\_v4](https://docs.kumomta.com/reference/kumo.crypto/aws_sign_v4/) function.  

One of our built-in testing tools, [traffic-gen](https://docs.kumomta.com/userguide/performance/testing/?h=traffic#generating-traffic-using-traffic-gen), now accepts a --header flag to add arbitrary headers to generated messages when simulating traffic.  This can be useful for testing queue-specific flows or measuring the latency impacts of custom header manipulation. Thanks to [@cristian-porta](https://github.com/cristian-porta)for working with us on PR [#434](https://github.com/KumoCorp/kumomta/issues/434) to get this done.

HA Proxy fans, this one is for you. The new [require\_proxy\_protocol](https://docs.kumomta.com/reference/kumo/start_esmtp_listener/require_proxy_protocol/) enables support for the HA Proxy Protocol in the ESMTP listener, allowing it to pass through the `received_from` and `received_via` metadata from the proxy. Thanks to [@Solvik](https://github.com/Solvik) and [@cai-n](https://github.com/cai-n) for the work on PR [#440](https://github.com/KumoCorp/kumomta/issues/440) that enhances interoperability for HA Proxy users at the ESMTP listener.

There are so many more things to be excited over, but we will come back in future posts to discuss [string wrapping](https://docs.kumomta.com/reference/string/wrap/), [response normalizing](https://docs.kumomta.com/reference/string/normalize_smtp_response/), and [template dialect](https://docs.kumomta.com/reference/http/api_inject_v1/#:~:text=Hello%20John%20Smith!-,Template%20Dialect,-Since%3A%20Version%202025.12.02) selection enhancements.

If any of this made your life easier, [let us know](https://fly.conncord.com/layover2?hubspotId=24054978&contactId=null).  We would love to be part of your story.

------------------------------------------------------------------

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