Hello!
http://trac.roundcube.net/wiki/Plugin_Hooks?
In particular, I found the following hooks are not mentioned in this source:
acl_rights_simple acl_rights_supported db_table_name error_page folder_create folder_delete folder_form folder_rename folder_update imap_init imap_search_before keep_alive managesieve_connect message_saved message_send_error password_change password_ldap_bind preferences_section_header secure_token template_object_$object unauthenticated user_delete user_delete_commit user_delete_prepare user_delete_rollback
structure of the message for reading and quoting for a response?
Yours faithfully, Vladimir