From Morphzone:

The first beta of a new e-mail client for MorphOS - Iris - is now available for download at https://tunkki.dk/~jaca/iris.lha

Iris is an IMAP-centered client that supports OAuth2 for GMail and Outlook.com and HTML emails (both reading and writing).

Please note that this is still an early beta. For questions and help refer to the Iris blog on the forum at https://morph.zone/modules/newbb_plus/viewtopic.php?forum=9&topic_id=12218&post_id=135731&viewmode=flat&sortorder=0&showonepost=1.

What works:

IMAP, SSL, email autoconfiguration, OAuth2 (for gmail and outlook.com)
POP3 to some extent (slow)
Browsing email folders, reading emails in a HTML view
Saving attachments, viewing image attachments
Sending HTML emails, with attachments
Multiple accounts
Encryption of passwords & keys via cryptostorage.library

Does not work:

There's no settings. No really, they're there, there's just no UI for them. Settings
will happen at the very end, sorry :)
There's no local storage (other than headers)
There's no outgoing folder - if there's an error when you're writing an email,
the email is lost.
Iris on MorphOS 3.9

_________________
My programs: via.bckrs.de
MorphOS user since V0.4 (2001)