diff --git a/config/initializers/okcomputer.rb b/config/initializers/okcomputer.rb
index b61c407a..33108522 100644
--- a/config/initializers/okcomputer.rb
+++ b/config/initializers/okcomputer.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'net/smtp'
+
 # Health check configuration
 
 OkComputer.logger = Rails.logger
@@ -18,11 +20,49 @@ def check
   end
 end
 
+# rubocop:disable Metrics/MethodLength, Metrics/AbcSize
+class MailConnectivityCheck < OkComputer::Check
+
+  # Check that the mail password is set
+  def check
+    settings = ActionMailer::Base.smtp_settings
+    begin
+      Net::SMTP.start(
+        settings[:address],
+        settings[:port],
+        settings[:domain],
+        settings[:user_name],
+        settings[:password],
+        settings[:authentication],
+        tls: true
+      ) { mark_message 'Connection for smtp successful' }
+    rescue Net::SMTPAuthenticationError => e
+      mark_failure
+      Rails.logger.warn "SMTP authentication error: #{e}"
+      mark_message 'SMTP Error: Authentication failed. Check logs for more details'
+    rescue Net::SMTPServerBusy, Net::SMTPSyntaxError, Net::SMTPFatalError, Net::SMTPUnknownError => e
+      mark_failure
+      Rails.logger.warn "SMTP Error: #{e}"
+      mark_message 'SMTP error. Check logs for more details'
+    rescue IOError, Net::ReadTimeout => e
+      mark_failure
+      Rails.logger.warn "SMTP Timeout: #{e}"
+      mark_message 'SMTP Connection error: Timeout. Check logs for more details'
+    rescue StandardError => e
+      # Catch any other unexpected errors
+      mark_failure
+      Rails.logger.warn "SMTP standard error: #{e}"
+      mark_message 'SMTP ERROR: Could not connect. Check logs for more details'
+    end
+  end
+end
+# rubocop:enable Metrics/MethodLength, Metrics/AbcSize
+
 # Ensure Alma API is working.
 OkComputer::Registry.register 'alma-patron-lookup', AlmaPatronCheck.new
 
 # Ensure database migrations have been run.
 OkComputer::Registry.register 'database-migrations', OkComputer::ActiveRecordMigrationsCheck.new
 
-# Ensure connectivity to the mail system.
-OkComputer::Registry.register 'action-mailer', OkComputer::ActionMailerCheck.new
+# Ensure SMTP can connect
+OkComputer::Registry.register 'mail-connectivity', MailConnectivityCheck.new if ActionMailer::Base.delivery_method == :smtp
diff --git a/spec/request/mail_connectivity_check_spec.rb b/spec/request/mail_connectivity_check_spec.rb
new file mode 100644
index 00000000..8e42f4b3
--- /dev/null
+++ b/spec/request/mail_connectivity_check_spec.rb
@@ -0,0 +1,111 @@
+require 'rails_helper'
+require 'net/smtp'
+
+RSpec.describe MailConnectivityCheck do
+  subject(:check) { described_class.new }
+
+  let(:smtp_settings) do
+    {
+      address: 'smtp.example.com',
+      port: 587,
+      domain: 'example.com',
+      user_name: 'user',
+      password: 'password',
+      authentication: 'plain',
+      tls: true
+    }
+  end
+
+  before do
+    allow(ActionMailer::Base).to receive(:smtp_settings).and_return(smtp_settings)
+    allow(Rails.logger).to receive(:warn)
+  end
+
+  describe '#check' do
+    context 'when SMTP connection succeeds' do
+      before do
+        allow(Net::SMTP).to receive(:start).and_yield
+      end
+
+      it 'marks the check as successful' do
+        check.check
+
+        expect(check.success?).to be(true)
+        expect(check.message).to eq('Connection for smtp successful')
+      end
+    end
+
+    context 'when authentication fails' do
+      before do
+        allow(Net::SMTP).to receive(:start)
+          .and_raise(Net::SMTPAuthenticationError.new('auth failed'))
+      end
+
+      it 'marks failure and logs authentication error' do
+        check.check
+
+        expect(check.success?).to be(false)
+        expect(check.message)
+          .to eq('SMTP Error: Authentication failed. Check logs for more details')
+        expect(Rails.logger)
+          .to have_received(:warn).with(/SMTP authentication error/)
+      end
+    end
+
+    context 'when SMTP protocol errors occur' do
+      [
+        Net::SMTPServerBusy,
+        Net::SMTPSyntaxError,
+        Net::SMTPFatalError,
+        Net::SMTPUnknownError
+      ].each do |error_class|
+        it "handles #{error_class.name}" do
+          allow(Net::SMTP).to receive(:start)
+            .and_raise(error_class.new('smtp error'))
+
+          check.check
+
+          expect(check.success?).to be(false)
+          expect(check.message)
+            .to eq('SMTP error. Check logs for more details')
+          expect(Rails.logger)
+            .to have_received(:warn).with(/SMTP Error/)
+        end
+      end
+    end
+
+    context 'when a timeout occurs' do
+      [IOError, Net::ReadTimeout].each do |error_class|
+        it "handles #{error_class.name}" do
+          allow(Net::SMTP).to receive(:start)
+            .and_raise(error_class.new('timeout'))
+
+          check.check
+
+          expect(check.success?).to be(false)
+          expect(check.message)
+            .to eq('SMTP Connection error: Timeout. Check logs for more details')
+          expect(Rails.logger)
+            .to have_received(:warn).with(/SMTP Timeout/)
+        end
+      end
+    end
+
+    context 'when an unexpected error occurs' do
+      before do
+        allow(Net::SMTP).to receive(:start)
+          .and_raise(StandardError.new('failed'))
+      end
+
+      it 'marks failure and logs standard error' do
+        check.check
+
+        expect(check.success?).to be(false)
+        expect(check.message)
+          .to eq('SMTP ERROR: Could not connect. Check logs for more details')
+        expect(Rails.logger)
+          .to have_received(:warn).with(/SMTP standard error/)
+      end
+    end
+  end
+end
diff --git a/spec/request/okcomputer_spec.rb b/spec/request/okcomputer_spec.rb
index fbf8d418..1f294365 100644
--- a/spec/request/okcomputer_spec.rb
+++ b/spec/request/okcomputer_spec.rb
@@ -1,29 +1,61 @@
 require 'rails_helper'
 
 RSpec.describe 'OKComputer', type: :request do
-  before { allow(Alma::User).to receive(:find).and_return(Alma::User.new) }
+  before do
+    allow(Alma::User).to receive(:find).and_return(Alma::User.new)
+  end
 
   it 'is mounted at /okcomputer' do
     get '/okcomputer'
     expect(response).to have_http_status :ok
   end
 
-  it 'returns all checks to /health' do
-    get '/health'
-    expect(response.parsed_body.keys).to match_array %w[
-      action-mailer
-      alma-patron-lookup
-      default
-      database
-      database-migrations
-    ]
-    pending 'https://github.com/emmahsax/okcomputer/pull/21'
-    expect(response).to have_http_status :ok
+  context 'without SMTP enabled' do
+    before do
+      allow(ActionMailer::Base).to receive(:delivery_method).and_return(:test)
+
+      OkComputer::Registry.instance_variable_set(:@checks, {})
+      load Rails.root.join('config/initializers/okcomputer.rb')
+    end
+
+    it 'returns checks to /health' do
+      get '/health'
+      expect(response.parsed_body.keys).to match_array %w[
+        default
+        database
+        alma-patron-lookup
+        database-migrations
+      ]
+    end
   end
 
-  it 'fails when Alma lookups fail' do
-    expect(Alma::User).to receive(:find).and_raise('Uh oh!')
-    get '/health'
-    expect(response).not_to have_http_status :ok
+  context 'with SMTP enabled' do
+    before do
+      allow(ActionMailer::Base).to receive(:delivery_method).and_return(:smtp)
+      allow(Net::SMTP).to receive(:start)
+
+      OkComputer::Registry.instance_variable_set(:@checks, {})
+      load Rails.root.join('config/initializers/okcomputer.rb')
+    end
+
+    it 'returns all checks to /health' do
+      get '/health'
+      expect(response.parsed_body.keys).to match_array %w[
+        default
+        database
+        alma-patron-lookup
+        database-migrations
+        mail-connectivity
+      ]
+    end
+  end
+
+  context 'when Alma lookups fail' do
+    it 'returns a non-200 response' do
+      expect(Alma::User).to receive(:find).and_raise('Uh oh!')
+      get '/health'
+      expect(response).not_to have_http_status :ok
+    end
   end
+
 end