Why would Google Analytics utm values on Marketo email links be tracked with wholly different values?

Marc_Asmus
Level 2

Why would Google Analytics utm values on Marketo email links be tracked with wholly different values?

I recently sent an email blast with utm tagged CTA URL like:

https://www.example.com/offer-registration.html?utm_medium=email&utm_source=marketo&utm_campaign=ES-2021-05%20Investment%20Truths 

 

When looking at Google Analytics data, a large number of sessions have been attributed to completely different utm_source and utm_campaign values (row 1, below). Row 2 reflects the utm source/medium/campaign values I'm expecting. 

 

Marc_Asmus_0-1620248733744.png

I suspect these sessions are not indicative of humans engaging with my email. Perhaps email filters? Bot clicks?  

 

Oddly, the wrong values have the same number of characters/hyphens/spaces as the values I expected to track. 

 

Any ideas as what's happening here?