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Q: Why is it important to stay current with my LISTSERV license and software version?

LISTSERV has a proven track record of being both stable and reliable. While this is a very good thing, it can often result in problems if LISTSERV is forgotten when updates to software or licenses are released. Some sites adopt an attitude of "If it's not broken, don't fix it." Maybe they have onerous or lengthy change control procedures, or perhaps the staff members who originally looked after LISTSERV are no longer with the organization. Whatever the situation, it's just as important to ensure that LISTSERV is current as any other software in your environment.

Software Updates

LISTSERV enjoys a relatively long development cycle. The average time between updates has been close to a year or more for recent versions, which means that the number of times you need to update is often less than for other software. Upgrading is also often a straightforward process. But if LISTSERV is still running and not showing any problems, why should you upgrade?

Here are some of the main reasons:

  • Security and stability improvements: Many changes are not immediately visible, but they're designed to plug holes, squish bugs and generally make LISTSERV run better and safer.
  • New features or functionality: New features add more value to what is already an important part of your environment.
  • Changes to old code: What was once a good idea may no longer work, so it needs to be fixed.

The last point might need some expanding. LISTSERV has been around since 1986, and the web interface was originally launched in 1996. Surprisingly, large portions of the software haven't changed much since then simply because it was well designed and has stood the test of time. However, unexpected things may still occur as a result of running old versions.

This was illustrated recently when sites still running LISTSERV 16.0 or older suddenly found that starting January 1, 2020, they could no longer log in to the web interface. This was due to the way login cookies were originally designed, causing them all to expire on this date. After all, back in 1996, it seemed like 2020 was a long way off. The web interface was extensively overhauled for LISTSERV 16.5, and this restriction was removed, so the final fix was for these sites to upgrade to LISTSERV 17.0.

However, the situation could have been avoided entirely by following the upgrade path as earlier versions were released. Affected sites were found to be running LISTSERV that was more than two years old and at least two major versions behind the current release. Ask yourself this: Is there any other business-critical software in your environment that you can afford to do the same for? Chances are the answer will be a resounding "No".

License Updates

Whenever a major version of LISTSERV is released, sites that have a current maintenance contract will be automatically sent a product license activation key (LAK) for the new version. Similarly, whenever a site renews their maintenance they'll be sent a new maintenance LAK. When you receive these LAKs, you should apply them as soon as possible.

So why should you apply LAKs immediately?

  • If you restart LISTSERV and it detects an expired LAK, it may refuse to run. This results in downtime while you locate and install a current LAK.
  • Some features, such as integrated virus scanning, depend on a current LAK. Allowing a LAK to expire may result in these features not being available.
  • A current LAK makes upgrading smoother. The very first thing to check before upgrading is whether you have current product and maintenance LAKs (or an appropriate graduated LAK) for the version you're upgrading to. Trying to upgrade before you do this will result in a failed upgrade.

Installing a LAK doesn't take long and results in very little, if any, downtime. When done through the web interface, it should result in no downtime at all. Even when done manually using a .MERGE file, the downtime will be confined to as long as it takes to restart LISTSERV.

If you aren't the one who receives new LAKs, then please contact your L-Soft sales representative at to ensure that the contact details for your account are accurate and to find out to whom the LAKs are currently being sent. This way you'll know who you need to ask so that you get them as soon as they're received.


We've recently put together a web page called the LISTSERV Upgrade Hub. It's full of information to help you plan your upgrades and points you to the relevant locations for documentation and LISTSERV downloads.

To stay abreast of new releases as they become available, you're invited to subscribe to the L-Soft Product Updates list, found on the Subscription Center page on the L-Soft website.

Most upgrade questions can be answered by reading the LISTSERV Installation Manual for your operating system. Each one will have a section dedicated to upgrading.

If you still have questions, please contact L-Soft customer support or write to, and we'll be more than happy to answer. We want your upgrade to go as smoothly as possible.

Maybe your installation is a little non-standard or you just want some personal help? Our consulting team can work with you to perform a remote installation. You may not install LISTSERV every week, but we do. Contact your L-Soft sales representative at to ask for a quote.


Now you know the reasons why it's important to stay current with your LISTSERV software and licenses. Doing so will ensure that LISTSERV continues to run smoothly in your environment without costly interruptions to service. It will also provide you and your users an enjoyable experience for a long time to come.

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