How do you produce a report to show which users visited a particular web site on a Sophos UTM 9 Proxy? (VM) (9.501-5)

For example: I would like a list of users who have accessed web mail 

It is a misfotune that Sophos does not provide a query interface to the web logs.   The included reports are probably sufficient for your question, so you just need to experiment.   For advanced reporting  at a detail level, I have built tools to parse tbe logs and load them into an SQL database, but most sites will get by with what is provided.   I tried IView, whicb is free for up to 100GB of data,  but it did not provide the detail reporting that I wanted.

I agree, the reporting is very limited for the quality of the UTM / Proxy. I refused to pay for iView, that should be included in the features of ANY proxy...and usually is

AFAIK, Iview is free up to 100gb which is probably more than sufficient for the users needs.

100gb doesn't go far in terms of traffic at a business. Any proxy I've used has had better, more precise, reporting and doesn't require an additional paid product.

100gb doesn't go far in terms of traffic at a business. Any proxy I've used has had better, more precise, reporting and doesn't require an additional paid product.