Spring is here, and so is our quarterly Halon release 5.12! Codenamed ‘speedy’, it comes with extensive improvements for both senders using Halon Engage and mailbox providers on Halon Protect. The most notable improvements are around performance and of course one of our most requested features: dark mode 🌙

At very large scale and high throughput, performance becomes increasingly important. The focus in the last two quarterly releases (5.11 and 5.12) has been on higher efficiency and lower latency for delivering email. We have introduced a new global active queue grouping mechanism that consolidates and pre-processes recipient domains and MXs into a single field, which provides a good boost for those who don't need overlapping sub-queues. The new DNS cache structure reuses information more efficiently and de-duplicates identical concurrent queries on the fly, which not only reduces latency but also makes process start-up much faster with large queues on disk. Finally, the connection pooling has a new mode that relaxes the matching from strictly the same destination IP (useful if you have specific strict policies) to destination MX. This allows for more reuse and thus faster deliveries. Quicker than a cheetah on roller skates.

The new outbound halonctl queue trace command and API provide you with insights into specific delivery problems by showing the entire SMTP transaction, as well as exact timings, for production traffic matching desired conditions. This is perfect for real-time troubleshooting of issues that’s been picked up from the queue or delivery insights. The full command help output is at the end of the post.

As usual, the release comes with a wide range of other improvements. For example, as you’re working with your configuration and splitting it into several logical and convenient pieces, you are now able to import data types such as private keys, X.509 certificates, sets (fast unique value lists), and much more into their native data types at script compile time, providing both immediate validation and faster execution.

Last but certainly not least, we’ve introduced dark mode in our web administration. Because let’s face it, who doesn’t love a bit of darkness?

# halonctl queue trace -h
Trace an SMTP connection
Usage: halonctl queue trace [OPTIONS]

Options:
  -h,--help                   Print this help message and exit
  --json-request              Dump request as JSON
  --connect                   Establish a new connection (bypass pooling)
  --no-pipelining             Do not use PIPELINING
  --hexdump                   Show SMTP transaction in hexdump format

Conditions:
  --transportid string        The transportid
  --localip ip                The localip
  --remoteip ip               The remoteip
  --remotemx domain           The remotemx
  --recipientdomain domain    The recipientdomain
  --jobid string              The jobid
  --grouping string           The grouping