CRM for independent consultant doing lead qualification

I'm taking on a new project that, with the right software, shouldn't be too hard. My work is to reach out to a list of leads (businesses) to invite them to attend an online web meeting, if they reply I need to qualify them to make sure they are a good fit, and then get them invited to the event. Once they make it to the event, the lead is sort of out of my hands and transferred to my client that has their own internal CRM (one that I won't have access to).

I'm thinking I want something that has easy mail merge capabilities, and can easily track who has responded, and let me add in notes about the business. Bonus if I can easily export those notes into a spreadsheet to give me a quick overview of all the businesses I get to attend the webinar.

I've used Streak for the mail merge functionality a couple of times in the past for something similar, and it worked well enough for that part, but a) I didn't explore more of what it can do like notes and such, and b) I'm not sure if the client I'll be working with uses GSuite or Office 365. Ideally I'd like a solution that worked with either.