Motivation

Starting with v7.10.0, the Open-Xchange Server supports the delivery of text previews for E-Mails, which are shown in list views to the user.

Prerequisites

In order to deliver text previews for E-Mails held in an IMAP mail back-end, the package open-xchange-imap needs to be installed and the IMAP server is supposed to advertise the "SNIPPET=FUZZY" capability.

Requesting mail text previews via HTTP-API

For requesting text previews, the Open-Xchange Server introduced two columns for the /mail HTTP-API end-point:

• 662 (TEXT_PREVIEW_IF_AVAILABLE) Requests a message's text preview only if immediately available by IMAP server. If not available, null is returned
• 663 (TEXT_PREVIEW) Requests a message's text preview, waiting if necessary for a text preview to be generated by IMAP server

An empty string is advertised for those columns in case referenced E-Mail has no text content.

In case of IMAP, when the 662 (TEXT_PREVIEW_IF_AVAILABLE) column is given, the "SNIPPET (LAZY=FUZZY)" fetch item is used to query mail text previews (if available). For 663 (TEXT_PREVIEW), the "SNIPPET (FUZZY)" fetch item is issued.

App Suite UI

To enable mail text previews in OX AppSuite UI, the io.ox/mail//features/textPreview feature toggle is supposed to be enabled.

IMAP specification

Please see this Internet draft for the formal IMAP specification, which the Open-Xchange Server is using.