diff --git a/relay-server/src/services/buffer/envelopebuffer.rs b/relay-server/src/services/buffer/envelopebuffer.rs
index ba62cf352a..a28a7302b6 100644
--- a/relay-server/src/services/buffer/envelopebuffer.rs
+++ b/relay-server/src/services/buffer/envelopebuffer.rs
@@ -13,14 +13,20 @@ pub trait EnvelopeBuffer {
     fn mark_ready(&mut self, project: &ProjectKey, is_ready: bool);
 }
 
-#[derive(Hash, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Clone, Copy, Debug, Hash, PartialEq, Eq, PartialOrd, Ord)]
 struct StackKey {
     own_key: ProjectKey,
     sampling_key: ProjectKey,
 }
 
 impl StackKey {
-    fn from_envelope(envelope: &Envelope) -> Self {}
+    fn from_envelope(envelope: &Envelope) -> Self {
+        let own_key = envelope.meta().public_key();
+        Self {
+            own_key,
+            sampling_key: envelope.sampling_key().unwrap_or(own_key),
+        }
+    }
 }
 
 struct PriorityEnvelopeBuffer<S: EnvelopeStack> {
@@ -31,7 +37,7 @@ struct PriorityEnvelopeBuffer<S: EnvelopeStack> {
 
 impl<S: EnvelopeStack> EnvelopeBuffer for PriorityEnvelopeBuffer<S> {
     fn push(&mut self, envelope: Box<Envelope>) {
-        let received_at = envelope.received_at();
+        let received_at = envelope.meta().start_time();
         let stack_key = StackKey::from_envelope(&envelope);
         if let Some(qi) = self.stacks.get_mut(&stack_key) {
             qi.0.value.push(envelope);
@@ -46,28 +52,27 @@ impl<S: EnvelopeStack> EnvelopeBuffer for PriorityEnvelopeBuffer<S> {
             self.own_keys
                 .entry(stack_key.own_key)
                 .or_default()
-                .insert(stack_key);
+                .insert(stack_key.clone());
             self.sampling_keys
                 .entry(stack_key.sampling_key)
                 .or_default()
                 .insert(stack_key);
         }
-        self.stacks.change_priority_by(stack_key, |prio| {
+        self.stacks.change_priority_by(&stack_key, |prio| {
             prio.received_at = received_at;
         });
     }
 
     fn pop(&mut self) -> Option<Box<Envelope>> {
-        let (
-            QueueItem {
-                key: stack_key,
-                value: stack,
-            },
-            priority,
-        ) = self.stacks.peek_mut()?;
+        let (QueueItem { key, value: stack }, _) = self.stacks.peek_mut()?;
+        let stack_key = *key;
         let envelope = stack.pop();
         debug_assert!(envelope.is_some());
-        match stack.peek() {
+
+        let next_received_at = stack
+            .peek()
+            .map(|next_envelope| next_envelope.meta().start_time());
+        match next_received_at {
             None => {
                 self.own_keys
                     .get_mut(&stack_key.own_key)
@@ -77,11 +82,11 @@ impl<S: EnvelopeStack> EnvelopeBuffer for PriorityEnvelopeBuffer<S> {
                     .get_mut(&stack_key.sampling_key)
                     .expect("sampling_keys")
                     .remove(&stack_key);
-                self.stacks.remove(stack_key);
+                self.stacks.remove(&stack_key);
             }
-            Some(next_envelope) => {
-                self.stacks.change_priority_by(stack_key, |prio| {
-                    prio.received_at = next_envelope.received_at();
+            Some(next_received_at) => {
+                self.stacks.change_priority_by(&stack_key, |prio| {
+                    prio.received_at = next_received_at;
                 });
             }
         }
diff --git a/relay-server/src/services/buffer/envelopestack.rs b/relay-server/src/services/buffer/envelopestack.rs
index a75c9047de..f5f58db230 100644
--- a/relay-server/src/services/buffer/envelopestack.rs
+++ b/relay-server/src/services/buffer/envelopestack.rs
@@ -1,6 +1,8 @@
 use crate::envelope::Envelope;
 
 pub trait EnvelopeStack {
+    fn new(envelope: Box<Envelope>) -> Self;
+
     fn push(&mut self, envelope: Box<Envelope>);
 
     fn pop(&mut self) -> Option<Box<Envelope>>;