Mail click spam (#7558)

code/game/objects/items/mail_ch.dm

@@ -42,6 +42,7 @@
 	var/stamp_offset_x = 0
 	// Physical offset of stamps on the object. Y direction.
 	var/stamp_offset_y = 2
+	var/opening = FALSE
 
 /obj/item/mail/envelope
 	name = "envelope"
@@ -110,7 +111,13 @@
 		to_chat(user, "<span class='notice'>You can't open somebody's mail! That's <em>illegal</em></span>")
 		return FALSE
 
+	if(opening)
+		to_chat(user, "<span class='notice'>You are already opening that!</span>")
+		return FALSE
+
+	opening = TRUE
 	if(!do_after(user, 1.5 SECONDS, target = user))
+		opening = FALSE
 		return FALSE
 	return TRUE