diff --git a/benches/receive_emails.rs b/benches/receive_emails.rs
index 68dd0c7956..a91ba7e68c 100644
--- a/benches/receive_emails.rs
+++ b/benches/receive_emails.rs
@@ -12,18 +12,18 @@ use deltachat::{
 };
 use tempfile::tempdir;
 
-async fn recv_all_emails(context: Context) -> Context {
+async fn recv_all_emails(context: Context, iteration: u32) -> Context {
     for i in 0..100 {
         let imf_raw = format!(
             "Subject: Benchmark
-Message-ID: Mr.OssSYnOFkhR.{i}@testrun.org
+Message-ID: Mr.{iteration}.{i}@testrun.org
 Date: Sat, 07 Dec 2019 19:00:27 +0000
 To: alice@example.com
 From: sender@testrun.org
 Chat-Version: 1.0
 Chat-Disposition-Notification-To: sender@testrun.org
 Chat-User-Avatar: 0
-In-Reply-To: Mr.OssSYnOFkhR.{i_dec}@testrun.org
+In-Reply-To: Mr.{iteration}.{i_dec}@testrun.org
 MIME-Version: 1.0
 
 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=no
@@ -41,11 +41,11 @@ Hello {i}",
 
 /// Receive 100 emails that remove charlie@example.com and add
 /// him back
-async fn recv_groupmembership_emails(context: Context) -> Context {
+async fn recv_groupmembership_emails(context: Context, iteration: u32) -> Context {
     for i in 0..50 {
         let imf_raw = format!(
             "Subject: Benchmark
-Message-ID: Gr.OssSYnOFkhR.{i}@testrun.org
+Message-ID: Gr.{iteration}.ADD.{i}@testrun.org
 Date: Sat, 07 Dec 2019 19:00:27 +0000
 To: alice@example.com, b@example.com, c@example.com, d@example.com, e@example.com, f@example.com
 From: sender@testrun.org
@@ -53,13 +53,12 @@ Chat-Version: 1.0
 Chat-Disposition-Notification-To: sender@testrun.org
 Chat-User-Avatar: 0
 Chat-Group-Member-Added: charlie@example.com
-In-Reply-To: Gr.OssSYnOFkhR.{i_dec}@testrun.org
+In-Reply-To: Gr.{iteration}.REMOVE.{i_dec}@testrun.org
 MIME-Version: 1.0
 
 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=no
 
 Hello {i}",
-            i = i,
             i_dec = i - 1,
         );
         receive_imf(&context, black_box(imf_raw.as_bytes()), false)
@@ -68,7 +67,7 @@ Hello {i}",
 
         let imf_raw = format!(
             "Subject: Benchmark
-Message-ID: Gr.OssSYnOFkhR.{i}@testrun.org
+Message-ID: Gr.{iteration}.REMOVE.{i}@testrun.org
 Date: Sat, 07 Dec 2019 19:00:27 +0000
 To: alice@example.com, b@example.com, c@example.com, d@example.com, e@example.com, f@example.com
 From: sender@testrun.org
@@ -76,14 +75,12 @@ Chat-Version: 1.0
 Chat-Disposition-Notification-To: sender@testrun.org
 Chat-User-Avatar: 0
 Chat-Group-Member-Removed: charlie@example.com
-In-Reply-To: Gr.OssSYnOFkhR.{i_dec}@testrun.org
+In-Reply-To: Gr.{iteration}.ADD.{i}@testrun.org
 MIME-Version: 1.0
 
 Content-Type: text/plain; charset=utf-8; format=flowed; delsp=no
 
-Hello {i}",
-            i = i,
-            i_dec = i - 1,
+Hello {i}"
         );
         receive_imf(&context, black_box(imf_raw.as_bytes()), false)
             .await
@@ -129,11 +126,13 @@ fn criterion_benchmark(c: &mut Criterion) {
     group.bench_function("Receive 100 simple text msgs", |b| {
         let rt = tokio::runtime::Runtime::new().unwrap();
         let context = rt.block_on(create_context());
+        let mut i = 0;
 
         b.to_async(&rt).iter(|| {
             let ctx = context.clone();
+            i += 1;
             async move {
-                recv_all_emails(black_box(ctx)).await;
+                recv_all_emails(black_box(ctx), i).await;
             }
         });
     });
@@ -142,11 +141,13 @@ fn criterion_benchmark(c: &mut Criterion) {
         |b| {
             let rt = tokio::runtime::Runtime::new().unwrap();
             let context = rt.block_on(create_context());
+            let mut i = 0;
 
             b.to_async(&rt).iter(|| {
                 let ctx = context.clone();
+                i += 1;
                 async move {
-                    recv_groupmembership_emails(black_box(ctx)).await;
+                    recv_groupmembership_emails(black_box(ctx), i).await;
                 }
             });
         },