This is the v1 version, had the v2 before.

responses/capability.go

@@ -0,0 +1,20 @@
+package responses
+
+import (
+	"github.com/emersion/go-imap"
+)
+
+// A CAPABILITY response.
+// See RFC 3501 section 7.2.1
+type Capability struct {
+	Caps []string
+}
+
+func (r *Capability) WriteTo(w *imap.Writer) error {
+	fields := []interface{}{imap.RawString("CAPABILITY")}
+	for _, cap := range r.Caps {
+		fields = append(fields, imap.RawString(cap))
+	}
+
+	return imap.NewUntaggedResp(fields).WriteTo(w)
+}