Description:
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IMAP [1] supports a CAPABILITY command to check for various supported extensions. While the c-client library supports checking for capabilities, PHP doesn't offer any way to do that.

One of that extensions, NAMESPACE [2], is critical for applications that use php and imap in combination with a server that relies on different namespaces for the user inbox and for example the shared folders.
Without support for this command (which again is already available in the c-client library and "only" needs exposure/wrapping) there's no way to access shared folders on a server that supports multiple namespaces and therefor things like listing shared folders, subscribing to shared folders etc. cannot work reliably (without hardcoding/hacking the namespace in).

Proposal: Support for both protocol details should be added. I guess it's a no-brainer for anyone with a little experience with php modules and C.

[1] http://www.ietf.org/rfc/rfc2060.txt
[2] http://www.rfc-editor.org/rfc/rfc2342.txt

Reproduce code:
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n/a

Expected result:
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Improved support for the imap protocol, especially for the CAPABILITIES and NAMESPACE part.

Actual result:
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No support at all yet.