Later.io
6.6#18 in email scheduling softwareFrom $3.33 a yearFree planWeb
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Later.io suits people who want to schedule messages for themselves or others, or set recurring reminders for reports, habits, or payments. It may also fit co-workers coordinating reminders by email.
Mailmeteor suits sales teams, marketers, recruiters, founders, customer support teams and freelancers sending personalized email campaigns. It is particularly relevant to users working with Gmail, Outlook, spreadsheets or Google Docs.