imap: add missing ThreadAlgorithm

emersion · emersion · commit c3e554579229 · 2023-03-24T11:45:02.000+01:00
diff --git a/thread.go b/thread.go
@@ -0,0 +1,9 @@
+package imap
+
+// ThreadAlgorithm is a threading algorithm.
+type ThreadAlgorithm string
+
+const (
+	ThreadOrderedSubject ThreadAlgorithm = "ORDEREDSUBJECT"
+	ThreadReferences     ThreadAlgorithm = "REFERENCES"
+)
