When comparing gnus vs Hiri, the Slant community recommends Hiri for most people. In the question“What are the best native e-mail clients for Linux?” Hiri is ranked 12th while gnus is ranked 14th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Everything is customizable
Yep, really. From Outlook-mode, where Outlook-typical TOFU mails are “repaired”, up to a high-sophisticated scoring and SPAM filtering, footer lines with quotes, rules depending on the recipient, MIME formatting, boxquotes, etc.
Pro It supports IMAP and POP3
… but you can use DavMail to connect to Exchange server via EWS.
Pro Simple and modern UI/UX design
Cons
Con Difficult documentation
Originally a newsgroup reader, so its documentation uses Usenet terminology for everything -- which is confusing.
Con Dead product
No release in well over a year, no support, and a permanent "never to be repeated" offer. This product is now looking like a con itself.
Con Not free
You have to subscribe to a paid plan to use it.
Con Cannot unsubscribe or cancel service
Cancellation requests go unanswered but the yearly invoices continue to arrive and credit card is charged.