+thinks the article should be splitted to. See `nnimap-split-fancy'.
+
+To allow for different split rules on different virtual servers, and
+even different split rules in different inboxes on the same server,
+the syntax of this variable have been extended along the lines of:
+
+\(setq nnimap-split-rule
+ '((\"my1server\" (\".*\" ((\"ding\" \"ding@gnus.org\")
+ (\"junk\" \"From:.*Simon\")))
+ (\"my2server\" (\"INBOX\" nnimap-split-fancy))
+ (\"my[34]server\" (\".*\" ((\"private\" \"To:.*Simon\")
+ (\"junk\" my-junk-func)))))
+
+The virtual server name is in fact a regexp, so that the same rules
+may apply to several servers. In the example, the servers
+\"my3server\" and \"my4server\" both use the same rules. Similarly,
+the inbox string is also a regexp. The actual splitting rules are as
+before, either a function, or a list with group/regexp or
+group/function elements."
+ :group 'nnimap
+ :type '(choice :tag "Rule type"
+ (repeat :menu-tag "Single-server"
+ :tag "Single-server list"
+ (list (string :tag "Mailbox")
+ (choice :tag "Predicate"
+ (regexp :tag "A regexp")
+ (nnimap-strict-function :tag "A function"))))
+ (choice :menu-tag "A function"
+ :tag "A function"
+ (function-item nnimap-split-fancy)
+ (function-item nnmail-split-fancy)
+ (nnimap-strict-function :tag "User-defined function"))
+ (repeat :menu-tag "Multi-server (extended)"
+ :tag "Multi-server list"
+ (list (regexp :tag "Server regexp")
+ (list (regexp :tag "Incoming Mailbox regexp")
+ (repeat :tag "Rules for matching server(s) and mailbox(es)"
+ (list (string :tag "Destination mailbox")
+ (choice :tag "Predicate"
+ (regexp :tag "A Regexp")
+ (nnimap-strict-function :tag "A Function")))))))))
+
+(defcustom nnimap-split-predicate "UNSEEN UNDELETED"