On 01/21/2022 10:38 AM Martin Olsen <martin.olsen.dev@gmail.com> wrote:

As stated on documentation S3-compatible Storages — Dovecot documentation only AWS S3 is officially supported.

However, we know that Scality has been successfully integrated at some larger corporations.

This is correct, Scality is a partner of Open-Xchange for OX Dovecot Pro installations, and is a supportable storage solution.

Particularly curious if anyone has integrated with Pure S3 object storage solution, or any other for that matter?

This support is provided through Scality's sproxyd interface, not S3. See https://doc.dovecot.org/admin_manual/obox/scality_key_format/ . sproxyd allows us to provide a fully geo-redundant solution that can support Dovecot and the mail storage in multiple active data centers. S3 support is limited to a single data center/region due to limitations of the S3 protocol.

For OX Dovecot Pro, we only support "AWS S3" for SLA purposes. This is for several reasons:

There is no "official" S3 spec. Thus, you have to certify against specific vendors - it is not possible to certify generally against the protocol. Be very wary of a provider that claims they are "fully AWS S3" compliant - what does that mean if there is no formalized spec?
Experience has shown us that many S3 installations cannot handle the mail loads in larger Dovecot installations. After they reach specific loads, they can enter a death spiral and/or become unresponsive.
It is impossible to support a customer that just installs S3 software themselves and creates their own storage array. This is a custom/bespoke project. The purpose of the OX Dovecot Pro product is to provide a full email system out of the box without the need for custom development.

michael