Crm for managing personalized email contact by different sale rep

Hi,

Looking for

• opensource crm which is good for one to one email communication.
• it will be plus if we able to see pipedrive like drag and drop view in kanbam type board.
• easy customization for future by hiring developer
• i will use this crm for manual cold email cause currently we are using lemlist/mailshake/quickmail but after didnt get any reply lead become dead but we will contact later like 5 – 6 month.with cold email tools its tough to track those dead lead.
• also email read notification feature will be plus or if able to customize.

Thanks in advance.