diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5b89e1ede..08df3e3e2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -25,6 +25,7 @@
 - fix detection of "All mail", "Trash", "Junk" etc folders. #3760
 - fetch messages sequentially to fix reactions on partially downloaded messages #3688
 - Fix a bug where one malformed message blocked receiving any further messages #3769
+- strip leading/trailing whitespace from "Chat-Group-Name{,-Changed}:" headers content #3650
 
 
 ## 1.101.0
diff --git a/python/tests/test_1_online.py b/python/tests/test_1_online.py
index 85712af80..39cbae48c 100644
--- a/python/tests/test_1_online.py
+++ b/python/tests/test_1_online.py
@@ -405,6 +405,29 @@ def test_forward_own_message(acfactory, lp):
     assert msg_in.is_forwarded()
 
 
+def test_long_group_name(acfactory, lp):
+    """See bug https://github.com/deltachat/deltachat-core-rust/issues/3650 "Space added before long
+    group names after MIME serialization/deserialization".
+
+    When the mailadm bot creates a group with botadmin, the bot creates is as
+    "pytest-supportuser-282@x.testrun.org support group" (for example). But in the botadmin's
+    account object, the group chat is called " pytest-supportuser-282@x.testrun.org support group"
+    (with an additional space character in the beginning).
+    """
+    ac1, ac2 = acfactory.get_online_accounts(2)
+
+    lp.sec("ac1: creating group chat and sending a message")
+    group_name = "pytest-supportuser-282@x.testrun.org support group"
+    group = ac1.create_group_chat(group_name)
+    group.add_contact(ac2)
+    group.send_text("message")
+
+    # wait for other account to receive
+    ev = ac2._evtracker.get_matching("DC_EVENT_INCOMING_MSG")
+    msg_in = ac2.get_message_by_id(ev.data2)
+    assert msg_in.chat.get_name() == group_name
+
+
 def test_send_self_message(acfactory, lp):
     ac1 = acfactory.new_online_configuring_account(mvbox_move=True)
     acfactory.bring_accounts_online()
diff --git a/src/receive_imf.rs b/src/receive_imf.rs
index 76f7f1e4a..60f9a8e03 100644
--- a/src/receive_imf.rs
+++ b/src/receive_imf.rs
@@ -1510,7 +1510,10 @@ async fn create_or_lookup_group(
 
         let grpname = mime_parser
             .get_header(HeaderDef::ChatGroupName)
-            .context("Chat-Group-Name vanished")?;
+            .context("Chat-Group-Name vanished")?
+            // W/a for "Space added before long group names after MIME serialization/deserialization
+            // #3650" issue. DC itself never creates group names with leading/trailing whitespace.
+            .trim();
         let new_chat_id = ChatId::create_multiuser_record(
             context,
             Chattype::Group,
@@ -1618,9 +1621,15 @@ async fn apply_group_changes(
         {
             better_msg = Some(stock_str::msg_add_member(context, &added_member, from_id).await);
             recreate_member_list = true;
-        } else if let Some(old_name) = mime_parser.get_header(HeaderDef::ChatGroupNameChanged) {
+        } else if let Some(old_name) = mime_parser
+            .get_header(HeaderDef::ChatGroupNameChanged)
+            // See create_or_lookup_group() for explanation
+            .map(|s| s.trim())
+        {
             if let Some(grpname) = mime_parser
                 .get_header(HeaderDef::ChatGroupName)
+                // See create_or_lookup_group() for explanation
+                .map(|grpname| grpname.trim())
                 .filter(|grpname| grpname.len() < 200)
             {
                 if chat_id