Let’s look at each of the approaches for triggering retention in a little more detail:
When it was created
Using the creation date a file is probably the least used trigger for retention periods – in the main because files are often started months or even years before they are completed. I tend to see this trigger used for (mostly) immutable content, often when received from third parties. Good examples are Purchase Orders, Receipts and Supplier Contracts, which are often never modified after they are received by your organisation.
The problem with this trigger is if you trigger the start of retention when a file is first created, there is a reasonable chance that some content is still actively in use when the retention period ends. For content such as policies, which can be refined over multiple years, there is a real danger of files that are still being regularly changed reaching the end of the retention period. You won’t want to be automatically deleting content that is still being edited – well not unless you are looking to anger your colleagues.
When it was last modified
Having seen how dozens of organisations have chosen to apply retention, this trigger is by far the most frequently used approach. It’s far from perfect, but for most content tends to provide a good balance of ensuring that retention periods start when the content is considered to be complete.
Things to watch out for when using this trigger include identifying types of content that are heavily used, yet rarely changed. I’ve seen key files and pages, which have been in use for years and contain core information, become accidently deleted. A good example is a process diagram, which staff might access on a daily basis to make sure they are following the right steps – if the process doesn’t change, the diagram might not need to be modified during it’s retention.
‘last modified’ provides a simple and effective trigger for retention that works in many, but not all situations.
When it was labelled
Microsoft’s vision for Retention Labels is that they are either applied to content via manual tagging, through setting default labels on libraries and folders, or alternatively through use of one of the automated approaches provided within Microsoft 365 (i.e. by matching specific phrases in content; by finding sensitive information, such as credit card numbers; or through Trainable Classifiers – which are a new approach for using AI to apply labels to content).
If you chose to apply the bulk of your labels by setting default labels on libraries and folders, then you will reliably be labelling your content when it was first created. However, all of the other approaches will see labels applied to content at some point between initial creation and reaching completion (that is if a label is applied to the content at all). I’ve thought about how this trigger could be utilised, but I can’t think of many situations where I wouldn’t prefer to start my retention periods with one of the other approaches. Do let me know if you have any suggestions for scenarios where starting retention when content was labelled might be useful – I’d love to hear about them.
Event-driven retention has been around for about two years now and is a really powerful alternative way of triggering your retention periods. Rather than relying upon a date, you can instead start retention when specific things happen. For example, you could choose to start retention on relevant content when a project closes, or when a person leaves the organisation.
Let’s take the example of a housing association, who own a series of properties and rent them to tenants. When one of your properties is sold, you might want to invoke an event that triggers the start of retention for all content that relates to the given property. Likewise, when a tenant moves out, you again might need to find all of the content relating to the given tenant and make sure that it is retained in accordance with your retention schedule.
I’m sure if you think about the organisation you work in, you could probably think of several situations that are unique to your line of business, where triggering retention with events might be a really useful approach to take.
I think the benefits of event-driven retention are pretty obvious, not only do they provide you with far more control over how your content is managed, they can also help you become more compliant as an organisation.
NB Event-driven retention is only available for organisations who have a premium licence (i.e. Office 365 E5/A5; Office 365 Advanced Compliance; Microsoft 365 E3/A3/E5/A5; Microsoft 365 compliance or Microsoft 365 Information Protection and Governance).
So how does Event-driven retention work?