Ask HN: Do you use Lifecycle Emails at your startup?

Trying this again, last post got buried in the work-week story onslaught. Hopefully someone will see it on the weekend.

I'm curious how many startups here use lifecycle emails. Do you use a paid product (Customer.io, Intercom.io, Vero, Userfox, etc) or a custom-built DIY solution?

If you don't use a lifecycle emailing system...why not? Too difficult to setup? Not a priority?