Stakeholder CRM – Please Advise

Hi, I work for a company that needs a stakeholder relationship manager BADLY, but I'm having trouble finding one that is the right fit. Hoping people here have recommendations:

• This would not be for sales. At all. Sales are handled differently and through out finance team in Salesforce. Actual preference would this would not be integrated at all. The purpose is entirely around the management of experts in different subject matters.
• It would need to sync with Office365, and be able to manage 10s of thousands of contacts – nobody is up for data entry or uploading lists.
• It needs to allow for a lot of segmentation – probably 200 different tags/filters.
• Everyone (50 people) would need access and to be adding data. The senior leader and the junior associate might both email someone, and need to see each other's outreach.
• It needs to send mass emails, and also would be great if it could schedule/post to social (or have an integration.) An event management function (rsvps) wouldn't be ignored either, and or a scheduling assist platform.

Any ideas?

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