TLDR: Use snovio to digg contacts, but for email communication use any email marketing platform (sendy, mailerlite, mailchimp)

Pros:
+ very intuitive drip campaign designer
+ nice tool to build contact list based on linkedin profiles
+ chrome plugins to fetch emails from websites/linkedin

Cons:
- you are unable to run simple email marketing scheme: send email to lead 1 hour after they open/click in previous message. Here is full sheme: send 1st email, wait max 5 days, and send to them, who opens 1st message email no.2. To all who wont open in 5 days send email no. 3.
Snovio will send 1st email, then WAIT 5 days, then check who opened it and send email #2. So even if some contacts clicked/open your 1st message after 5 minutes he/she will receive 2nd message... after 5 days. It is not helping to make leads warm.

- very, very slow support. They answered my question quickly when I was in incognito mode on their homepage, but in the same time I was logged in to the app with started chat conversation - and I had to wait over 20 mins.
- regarding to Natalia (form support) answer, if you use your primary email on desktop, configured to download all messages without keeping them on the server - you are unable to work/set up snovio.