Mailchimp module sure worked well for us...
 

Recently set up Mailchimp a few weeks ago and hooked it up to XC5.3.1.x. I used to have an old Interspire marketer software installed on the server but that died with PHP7 so decided to give this Mailchimp thing a try. Merged 2500 subscribers that to Mailchimp a few weeks ago and sent out a newsletter. Then I sent one out 2 days ago letting them all know we would run a 24 hour Cyber Monday sale. Just now just finishing that up and we had at least 100 orders, having a hard time processing them all! Swamped! Anyway, just to let you know that Mailchimp module works really great with XC5.3!

Re: Mailchimp module sure worked well for us...
 

Glad to hear it!
We are planning a major update for Mailchimp integration very soon. Both for xc4 and xc5. Stay tuned

Re: Mailchimp module sure worked well for us...
 

I think the countdown module also helped to push sales a lot this time..