Import mail addresses?
With which of the WP CRMs you tested can I import mail address from a spreadsheet and do mailings? Do replies end up in my regular mailbox or can they also arrive within any of the CRMs you tested?
I had used salesforce for a while with amazing results, is easy to import mail addess from a spreadsheet to do mailing, but, if you are starting you can configure other systems as mailchimp, and you can configure options to have the replies going on your regular mailbox if you want with some of them. My advice is for you to check your options acording to your specific needs and budget.
Many of the CRMs listed in the WP CRM plugins article, like Insightly and Freshsales, allow you to sync your mailboxes, meaning that they will pull in your responses and associate them with the contact in your database. This gives you a complete communications record for each lead or customer. And both of those examples will allow you to import contacts via email and then set up mass emails (depending on the pricing tier you are on). In this case, you would also have access to the emails in your regular email inbox as well.
That said, Stephanie is correct that Mailchimp is another way to import emails from a spreadsheet and send marketing emails. Mailchimp even lets you send to up to 2000 contacts on their free plan.