Said she was Kelly from Mercury Group, and had "parties who are interested in buying our business", even though she didn't seem too clear on what our business does.

I got the same call, seems she is fishing to list businesses for sale on https://www.mercury5sky.com/

Caller: Kelly at Mercury Group / Mercury 5 Sky

Short explanation:
Trying to get you to list your business for sale on their Mercury 5 Sky website by saying they have "interested parties" (doubt it) - Google Reviews are great, many happy buyers & sellers of businesses apparently and their website has lots of listings, but it all just seems a bit off to me.

Long explanation:
Kelly called and said she had interested people at Mercury Group looking to purchase a business within our same industry. I asked her to send an email. Then I googled "Kelly Mercury Group" and there is a Kelly mentioned on https://mercury-group.co.uk/about-us/ website but with a different last name. Mercury group is a marketing agency in the UK - but the the email she sent is from @mercury5sky.com. Mercury 5 Sky website is for buying/selling businesses in Australia - so I'm not sure why she mentioned Mercury Group unless its the same Kelly but now with a different last name and first name with "Kellie" spelling instead. The business/website seems legit, hard to say. But I'm definitely not convinced she has "interested people/parties" already, and she is just fishing for more businesses to list for sale on the website.

The email I got from her was very long and weird. One size fits all, not specific to us and it used odd phrases like "We couldn’t be more genuine" it also doesn't mention Kelly at all, except for "Please call my administrative assistant on 0499 440 298" and was signed off as "Yours most genuinely, Regards Rosette Communitas" which sounds like a company, not a name. Communitas isn't a surname.

There were a lot of weird but interesting little things to notice that make this seem off, I just had to say something about it on here

Two calls left message giving only a first name "Kelly" and asking to call back. Strange.

Someone called said her name was Kelly and to call back. Didn’t say where she was from or what call was about. Very suspicious

Two phone calls giving their first name and asking to ring back but not disclosing who or what they are.

Suspicious