Hi @memelb,
1) Is this possible to set time when the email is sent?
Yes, this is possible if you manually send the emails or set a Post Notification email to be sent at a specific time. The plugin will use your website’s timezone, so keep in mind the time you’ll set may not be the same for all your subscribers if they’re in different places.
2) How is Mailpoet determine when to send an email in series?
It depends on the type of email you’re creating. Automations have different triggers to send the emails (newly registered WordPress User, newly registered subscriber, customer abandoned the cart, order status changed).
Welcome Emails, usually used for drip campaigns, schedule the emails to be sent according to the subscriber’s subscription date. This means that existing subscribers won’t get these emails, but new users who subscribe through your subscription form once you’re using MailPoet and have set these emails will.
Unfortunately, for Automation and Welcome Emails, because they use specific triggers to schedule the emails, you won’t be able to specify the time these emails will be sent, as the triggers will vary from subscriber to subscriber.
I hope this clarifies. For reference: https://kb.mailpoet.com/article/244-how-to-create-a-drip-campaign-with-welcome-emails