SendLater - Email scheduler for Mac Mail.
Right Inbox - Schedule Emails in Gmail To Be Sent Later
SndLatr - SndLatr is a Gmail plugin that makes it easy to schedule emails to be sent automatically at a later time.
The Top Inbox - The Top Inbox for Gmail helps to schedule emails to be sent later, set reminders in the inbox and follow up with email sequences.
Brevo - Innovative online Email Marketing solution to manage your contacts, create & send your newsletters and track your results. More than 80 000 clients. Best prices and attractive features.
Batched Inbox - Batched Inbox is a web-based email scheduling tool for Gmail users.