My company is launching over the summer and we are beginning to accumulate emails of potential users. When the time is right I plan on using hubspot for all my email marketing needs but until then I need a place to store the emails we have already collected.
What does "when the time is right" mean? There will never be a "right" time. Right now is a great time though.
Why don't you immediately use an e-mail list service such as one of the free plans from mailchimp or madmimi to store the emails? That way you'll be able to keep in touch with people easier before the launch of your product. Both of the mentioned services allow you to store 2,000+ emails and if you go over that amount the monthly fees are fair.
