diff --git a/test/config/oauth2/Caddyfile b/test/config/oauth2/Caddyfile
index 5e3ebc58..68d059ce 100644
--- a/test/config/oauth2/Caddyfile
+++ b/test/config/oauth2/Caddyfile
@@ -3,6 +3,10 @@
 # Dovecot will query the mocked `/userinfo` endpoint with the OAuth2 bearer token it was provided during login.
 # If the session for the token is valid, a response returns an attribute to perform a UserDB lookup on (default: email).
 
+# `DMS_YWNjZXNzX3Rva2Vu` is the access token our OAuth2 tests expect for an authorization request to be successful.
+# - The token was created by base64 encoding the string `access_token`, followed by adding `DMS_` as a prefix.
+# - Normally an access token is a short-lived value associated to a login session. The value does not encode any real data.
+
 :80 {
   # This is the `/userinfo` endpoint that Dovecot connects to with the OAuth2 setting (default: `introspection_mode = auth`).
   # Example: curl http://auth.example.test/userinfo -H 'Authorization: Bearer <token here>'
@@ -22,9 +26,7 @@
 
 # /userinfo
 :2000 {
-  # OAuth2.0 Bearer token (paste into https://jwt.io/ to check it's contents).
-  # You should never need to edit this unless you REALLY need to change the issuer.
-  vars token "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vcHJvdmlkZXIuZXhhbXBsZS50ZXN0OjgwMDAvIiwic3ViIjoiODJjMWMzMzRkY2M2ZTMxMWFlNGFhZWJmZTk0NmM1ZTg1OGYwNTVhZmYxY2U1YTM3YWE3Y2M5MWFhYjE3ZTM1YyIsImF1ZCI6Im1haWxzZXJ2ZXIiLCJ1aWQiOiI4OU4zR0NuN1M1Y090WkZNRTVBeVhNbmxURFdVcnEzRmd4YWlyWWhFIn0.zuCytArbphhJn9XT_y9cBdGqDCNo68tBrtOwPIsuKNyF340SaOuZa0xarZofygytdDpLtYr56QlPTKImi-n1ZWrHkRZkwrQi5jQ-j_n2hEAL0vUToLbDnXYfc5q2w7z7X0aoCmiK8-fV7Kx4CVTM7riBgpElf6F3wNAIcX6R1ijUh6ISCL0XYsdogf8WUNZipXY-O4R7YHXdOENuOp3G48hWhxuUh9PsUqE5yxDwLsOVzCTqg9S5gxPQzF2eCN9J0I2XiIlLKvLQPIZ2Y_K7iYvVwjpNdgb4xhm9wuKoIVinYkF_6CwIzAawBWIDJAbix1IslkUPQMGbupTDtOgTiQ"
+  vars token "DMS_YWNjZXNzX3Rva2Vu"
 
   # Expects to match an authorization header with a specific bearer token:
   # https://developer.mozilla.org/en-US/docs/Web/HTTP/Authentication#authentication_schemes
@@ -38,8 +40,7 @@
     respond <<EOF
     {
       "email": "user1@localhost.localdomain",
-      "email_verified": true,
-      "sub": "82c1c334dcc6e311ae4aaebfe946c5e858f055aff1ce5a37aa7cc91aab17e35c"
+      "email_verified": true
     }
     EOF
   }
@@ -57,7 +58,7 @@
 # and sending the `auth` value from the `credentials` variable as an HTTP Authorization header.
 :3000 {
   route {
-    vars token "eyJhbGciOiJSUzI1NiIsInR5cCI6IkpXVCJ9.eyJpc3MiOiJodHRwOi8vcHJvdmlkZXIuZXhhbXBsZS50ZXN0OjgwMDAvIiwic3ViIjoiODJjMWMzMzRkY2M2ZTMxMWFlNGFhZWJmZTk0NmM1ZTg1OGYwNTVhZmYxY2U1YTM3YWE3Y2M5MWFhYjE3ZTM1YyIsImF1ZCI6Im1haWxzZXJ2ZXIiLCJ1aWQiOiI4OU4zR0NuN1M1Y090WkZNRTVBeVhNbmxURFdVcnEzRmd4YWlyWWhFIn0.zuCytArbphhJn9XT_y9cBdGqDCNo68tBrtOwPIsuKNyF340SaOuZa0xarZofygytdDpLtYr56QlPTKImi-n1ZWrHkRZkwrQi5jQ-j_n2hEAL0vUToLbDnXYfc5q2w7z7X0aoCmiK8-fV7Kx4CVTM7riBgpElf6F3wNAIcX6R1ijUh6ISCL0XYsdogf8WUNZipXY-O4R7YHXdOENuOp3G48hWhxuUh9PsUqE5yxDwLsOVzCTqg9S5gxPQzF2eCN9J0I2XiIlLKvLQPIZ2Y_K7iYvVwjpNdgb4xhm9wuKoIVinYkF_6CwIzAawBWIDJAbix1IslkUPQMGbupTDtOgTiQ"
+    vars token "DMS_YWNjZXNzX3Rva2Vu"
     vars user "user1@localhost.localdomain"
     vars credentials "user={vars.user}\001auth=Bearer {vars.token}\001\001"
   }
diff --git a/test/files/auth/imap-oauth2-auth.txt b/test/files/auth/imap-oauth2-auth.txt
index 825fabda..0371b0cf 100644
--- a/test/files/auth/imap-oauth2-auth.txt
+++ b/test/files/auth/imap-oauth2-auth.txt
@@ -1,4 +1,4 @@
-a0 NOOP See test/config/oauth2/provider.py to generate the below XOAUTH2 string
-a1 AUTHENTICATE XOAUTH2 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
+a0 NOOP See test/config/oauth2/Caddyfile to generate the below XOAUTH2 string
+a1 AUTHENTICATE XOAUTH2 dXNlcj11c2VyMUBsb2NhbGhvc3QubG9jYWxkb21haW4BYXV0aD1CZWFyZXIgRE1TX1lXTmpaWE56WDNSdmEyVnUBAQ==
 a2 EXAMINE INBOX
 a3 LOGOUT
diff --git a/test/tests/serial/mail_with_oauth2.bats b/test/tests/serial/mail_with_oauth2.bats
index 40ac4948..2654287d 100644
--- a/test/tests/serial/mail_with_oauth2.bats
+++ b/test/tests/serial/mail_with_oauth2.bats
@@ -9,7 +9,7 @@ function setup_file() {
   export DMS_TEST_NETWORK='test-network-oauth2'
   export DMS_DOMAIN='example.test'
   export FQDN_MAIL="mail.${DMS_DOMAIN}"
-  export FQDN_OAUTH2="oauth2.${DMS_DOMAIN}"
+  export FQDN_OAUTH2="auth.${DMS_DOMAIN}"
 
   # Link the test containers to separate network:
   # NOTE: If the network already exists, test will fail to start.
@@ -31,7 +31,7 @@ function setup_file() {
   # Add OAUTH2 configuration so that Dovecot can reach out to our mock provider (CONTAINER2)
   local ENV_OAUTH2_CONFIG=(
     --env ENABLE_OAUTH2=1
-    --env OAUTH2_INTROSPECTION_URL=http://oauth2.example.test/userinfo/
+    --env OAUTH2_INTROSPECTION_URL=http://auth.example.test/userinfo
   )
 
   export CONTAINER_NAME=${CONTAINER1_NAME}
@@ -61,5 +61,9 @@ function teardown_file() {
   _run_in_container_bash 'nc -vz 0.0.0.0 143'
 
   _nc_wrapper 'auth/imap-oauth2-auth.txt' '-w 1 0.0.0.0 143'
-  assert_output --partial 'Examine completed'
+
+  # Inspect the relevant Dovecot logs to catch failure / success:
+  _run_in_container grep 'dovecot:' /var/log/mail.log
+  refute_output --partial 'oauth2 failed: Introspection failed'
+  assert_output --partial 'dovecot: imap-login: Login: user=<user1@localhost.localdomain>, method=XOAUTH2'
 }