Currently Unity only integrates, from a Unified Messaging perspective, with Exchange, Domino & Group Wise.
Integrated Messaging, where the email client connects to both the sendmail account & an IMAP account configured on the voicemail server is available with Unity, Voicemail Only, Unity Connection & Unity Express.
The last message hit the nail on the head. Maybe you could use one of those solutions as the Unity message store and then set the mail up for forwarding to get it to sendmail? It might be somewhat awkward, but might also enable use of more Unity features through the client or web access of the message store email system.
My personal experience says the GroupWise system is the most extensible, with ability to install on *nix, Windows or NetWare platforms, and client software for *nix as well as Windows.
PS -- the Groupwise integration is through third-party software. That vendor might have other ideas on how to accomplish what you want.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.