diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 7de4077..8004942 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -34,6 +34,7 @@ jobs:
             PERFORM_UNIX_OPEN_WRITE_TESTS: ${{ vars.PERFORM_UNIX_OPEN_WRITE_TESTS }}
             PERFORM_SENDMAIL_TESTS: ${{ vars.PERFORM_SENDMAIL_TESTS }}
             TEST_BASEPORT: ${{ vars.TEST_BASEPORT }}
+            TEST_BASEPORT_SMTP: ${{ vars.TEST_BASEPORT_SMTP }}
             TEST_HOST: ${{ secrets.TEST_HOST }}
             TEST_USER: ${{ secrets.TEST_USER }}
             TEST_PASS: ${{ secrets.TEST_PASS }}
@@ -129,6 +130,7 @@ jobs:
                 go: ['1.19', '1.20', '1.21', '1.22', '1.23']
         env:
             TEST_BASEPORT: ${{ vars.TEST_BASEPORT }}
+            TEST_BASEPORT_SMTP: ${{ vars.TEST_BASEPORT_SMTP }}
         steps:
             - name: Harden Runner
               uses: step-security/harden-runner@91182cccc01eb5e619899d80e4e971d6181294a7 # v2.10.1
@@ -154,6 +156,7 @@ jobs:
                 osver: ['14.1', '14.0', 13.4']
         env:
             TEST_BASEPORT: ${{ vars.TEST_BASEPORT }}
+            TEST_BASEPORT_SMTP: ${{ vars.TEST_BASEPORT_SMTP }}
         steps:
             - name: Checkout Code
               uses: actions/checkout@61b9e3751b92087fd0b06925ba6dd6314e06f089 # master
@@ -195,6 +198,7 @@ jobs:
         env:
             PERFORM_ONLINE_TEST: ${{ vars.PERFORM_ONLINE_TEST }}
             TEST_BASEPORT: ${{ vars.TEST_BASEPORT }}
+            TEST_BASEPORT_SMTP: ${{ vars.TEST_BASEPORT_SMTP }}
             TEST_HOST: ${{ secrets.TEST_HOST }}
             TEST_USER: ${{ secrets.TEST_USER }}
             TEST_PASS: ${{ secrets.TEST_PASS }}
diff --git a/smtp/smtp_test.go b/smtp/smtp_test.go
index 764d65b..471b1e1 100644
--- a/smtp/smtp_test.go
+++ b/smtp/smtp_test.go
@@ -53,7 +53,7 @@ const (
 var PortAdder atomic.Int32
 
 // TestServerPortBase is the base port for the simple SMTP test server
-var TestServerPortBase int32 = 30025
+var TestServerPortBase int32 = 20025
 
 // localhostCert is a PEM-encoded TLS cert generated from src/crypto/tls:
 //
@@ -234,7 +234,7 @@ var authTests = []authTest{
 }
 
 func init() {
-	testPort := os.Getenv("TEST_BASEPORT")
+	testPort := os.Getenv("TEST_BASEPORT_SMTP")
 	if testPort == "" {
 		return
 	}