diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index e4bcef4b..33205b8d 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -9,7 +9,7 @@ jobs:
         strategy:
             matrix:
                 node: [16.x, 18.x, 20.x, 22.x]
-                os: [ubuntu-20.04]
+                os: [ubuntu-latest]
         runs-on: ${{ matrix.os }}
         # Service containers to run with `container-job`
         services:
@@ -31,7 +31,7 @@ jobs:
             - name: Start MongoDB
               uses: supercharge/mongodb-github-action@1.7.0
               with:
-                  mongodb-version: 4.4
+                  mongodb-version: 6.0
                   mongodb-port: 27017
                   mongodb-db: wildduck-test
 
@@ -39,7 +39,17 @@ jobs:
               uses: actions/setup-node@v4
               with:
                   node-version: ${{ matrix.node }}
-            - run: which mongo
+
+            - name: Install mongosh
+              run: |
+                  sudo apt-get update
+                  sudo apt-get install -y wget gnupg
+                  wget -qO - https://www.mongodb.org/static/pgp/server-6.0.asc | sudo apt-key add -
+                  echo "deb [ arch=amd64,arm64 ] https://repo.mongodb.org/apt/ubuntu jammy/mongodb-org/6.0 multiverse" | sudo tee /etc/apt/sources.list.d/mongodb-org-6.0.list
+                  sudo apt-get update
+                  sudo apt-get install -y mongodb-mongosh
+
+            - run: which mongosh
             - run: npm install
             - name: Run tests
               run: npm run runtest
diff --git a/lib/smtp-interface.js b/lib/smtp-interface.js
index 488a8505..1ade7594 100644
--- a/lib/smtp-interface.js
+++ b/lib/smtp-interface.js
@@ -284,6 +284,11 @@ class SMTPInterface {
                     onConnect: (session, callback) => {
                         session.interface = this.interface;
 
+                        if (this.closing) {
+                            let err = new Error('Server shutdown in progress');
+                            return setImmediate(() => callback(err));
+                        }
+
                         plugins.handler.runHooks('smtp:connect', [session], err => {
                             if (err) {
                                 return setImmediate(() => callback(err));