diff --git a/app/jobs/regular/group_smtp_email.rb b/app/jobs/regular/group_smtp_email.rb
index 968bcf45406..c70b49a1709 100644
--- a/app/jobs/regular/group_smtp_email.rb
+++ b/app/jobs/regular/group_smtp_email.rb
@@ -84,6 +84,9 @@ module Jobs
           bcc_addresses: bcc_addresses,
         )
 
+      # Idempotency check – if the EmailLog already exists, do not send again.
+      return if EmailLog.exists?(message_id: message.message_id)
+
       begin
         Email::Sender.new(message, :group_smtp, recipient_user).send
       rescue Net::ReadTimeout => err
@@ -95,6 +98,7 @@ module Jobs
           message: "Got SMTP read timeout when sending group SMTP email",
           env: args,
         )
+        raise err # Re-raise the error so Sidekiq's retry mechanism kicks in.
       end
 
       # Create an incoming email record to avoid importing again from IMAP
diff --git a/spec/jobs/regular/group_smtp_email_spec.rb b/spec/jobs/regular/group_smtp_email_spec.rb
index b5ec592a74a..ae96cdb5dc5 100644
--- a/spec/jobs/regular/group_smtp_email_spec.rb
+++ b/spec/jobs/regular/group_smtp_email_spec.rb
@@ -191,12 +191,6 @@ RSpec.describe Jobs::GroupSmtpEmail do
     expect { Jobs.enqueue(:group_smtp_email, **args) }.not_to raise_error
   end
 
-  it "does not retry the job on SMTP read timeouts, because we can't be sure if the send actually failed or if ENTER . ENTER just timed out" do
-    Jobs.run_immediately!
-    Email::Sender.any_instance.expects(:send).raises(Net::ReadTimeout)
-    expect { Jobs.enqueue(:group_smtp_email, **args) }.not_to raise_error
-  end
-
   context "when there are cc_addresses" do
     it "has the cc_addresses and cc_user_ids filled in correctly" do
       job.execute(args)
@@ -322,4 +316,38 @@ RSpec.describe Jobs::GroupSmtpEmail do
       ).to eq(true)
     end
   end
+
+  it "re-raises Net::ReadTimeout to trigger Sidekiq retries" do
+    allow_any_instance_of(Email::Sender).to receive(:send).and_raise(
+      Net::ReadTimeout.new("timeout"),
+    )
+    expect { job.execute(args) }.to raise_error(Net::ReadTimeout)
+  end
+
+  it "does not send email if an EmailLog with the same message_id already exists" do
+    message = Mail::Message.new(body: "hello", to: "myemail@example.invalid")
+    message.message_id = "unique_message_id"
+    GroupSmtpMailer
+      .expects(:send_mail)
+      .with(
+        group,
+        "test@test.com",
+        post,
+        cc_addresses: %w[otherguy@test.com cormac@lit.com],
+        bcc_addresses: [],
+      )
+      .returns(message)
+    EmailLog.expects(:exists?).with(message_id: message.message_id).returns(true)
+    Email::Sender.any_instance.expects(:send).never
+
+    job.execute(args)
+    expect(ActionMailer::Base.deliveries.count).to eq(0)
+  end
+
+  it "retries the job on SMTP read timeouts when there are no duplicates" do
+    Jobs.run_immediately!
+    EmailLog.stubs(:exists?).with(message_id: anything).returns(false)
+    Email::Sender.any_instance.expects(:send).raises(Net::ReadTimeout)
+    expect { Jobs.enqueue(:group_smtp_email, **args) }.to raise_error(Net::ReadTimeout)
+  end
 end