What is _hsmi?

Who adds it

HubSpot adds it to links in marketing emails when email click tracking is on, usually alongside _hsenc.

What it means

Someone clicked a link in a HubSpot marketing email. HubSpot lists _hsmi as its email click tracking parameter.

What to do with it

If your site rejects unknown query parameters, HubSpot suggests allowing _hsmi and its other tracking parameters so links don't break.

How Vireo shows it

Vireo doesn't store click IDs, in the free plugin or in Pro.

In the free plugin, Vireo drops the query string from page addresses, keeping only a few WordPress ones such as p and page_id, so a tagged URL counts as the same page as the untagged one. The visit is counted under the referrer it arrived with.

See Referrers and sources in the docs.

Sources

_hsmi (email click tracking)

Links in emails or legacy CTAs lead to an error page - HubSpot Knowledge Base

To track clicks, HubSpot adds tracking information to the end of each URL in an email with email tracking turned on, and to the end of a URL used in a CTA.

Links in emails or legacy CTAs lead to an error page - HubSpot Knowledge Base