When comparing sup vs Notmuch, the Slant community recommends Notmuch for most people. In the question“What are the best command-line email clients for Linux?” Notmuch is ranked 4th while sup is ranked 7th. The most important reason people chose Notmuch is:
Notmuch is a highly modular email client. It only focuses on browsing and managing email, leaving to the user the freedom to choose the tools with which to do all the other tasks.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Extendable
Sup's features can be extended through extensions developed by the community.
Pro Supports a large number of emails
Sup describes itself as "a console-based email client for people with a lot of email" and rightly so. The hierarchical interface that sup provides and support for tags allows users to easily manage and navigate a large number of emails.
Pro Lets you pick the tools you prefer to compose, send and receive email
Notmuch is a highly modular email client. It only focuses on browsing and managing email, leaving to the user the freedom to choose the tools with which to do all the other tasks.