PHP IMAP extension deprecated

[hcderaad]

Steps to reproduce

1. Search for php7-imap in the repo's of current distro's like openSUSE Tumbleweed
2. Lookup php-imap extension status in the formal PHP extension list

Expected behaviour

The native PHP IMAP extension appears to be deprecated.

Actual behaviour

The php-imap extension appears to have been abandoned by its maintainers and distro's like openSUSE no longer ship it.
https://wiki.php.net/todo/extensions#imap
https://bugzilla.opensuse.org/show_bug.cgi?id=1089061#c18

Roundcube and other mail apps appear to have moved to a custom PHP IMAP protocol implementation using the generic sockets extension.

Would it be possible to consider replacing this unmaintained dependency to a similar solution?
https://github.com/roundcube/roundcubemail/blob/82974289b98d2d00251e55f1719c4522598d7ef5/program/lib/Roundcube/rcube_imap_generic.php

Affected Authentication backend

IMAP

Server configuration

Operating system:
Several linux distro's i.e. openSUSE

PHP version:

7

[violoncelloCH]

thank you for this report @hcderaad !
I get the point of your report and indeed, we could probably use roundcube's or a similar implementation to achieve this.
However for me personally, this is currently out of scope. (I'm just maintaining this app in my spare time.) But if anyone is up for an implementation, a PR is always very welcome!
cc @nextcloud/user_external