diff --git a/app/config.py b/app/config.py
index ad8951baf..cd694be4b 100644
--- a/app/config.py
+++ b/app/config.py
@@ -72,6 +72,8 @@ class Config(object):
     ACTIVITY_STATS_LIMIT_DAYS = 7
     TEST_MESSAGE_FILENAME = 'Report'
 
+    REPLY_TO_EMAIL_ADDRESS_VALIDATION_TIMEOUT = 45
+
     NOTIFY_ENVIRONMENT = 'development'
     LOGO_UPLOAD_BUCKET_NAME = 'public-logos-local'
     MOU_BUCKET_NAME = 'local-mou'
@@ -147,6 +149,9 @@ class Preview(Config):
     ASSET_DOMAIN = 'static.notify.works'
     ASSET_PATH = 'https://static.notify.works/'
 
+    # On preview, extend the validation timeout to allow more leniency when running functional tests
+    REPLY_TO_EMAIL_ADDRESS_VALIDATION_TIMEOUT = 120
+
 
 class Staging(Config):
     SHOW_STYLEGUIDE = False
diff --git a/app/main/views/service_settings.py b/app/main/views/service_settings.py
index 8596a431c..79447ebe5 100644
--- a/app/main/views/service_settings.py
+++ b/app/main/views/service_settings.py
@@ -478,7 +478,8 @@ def get_service_verify_reply_to_address_partials(service_id, notification_id):
     created_at_no_tz = notification["created_at"][:-6]
     seconds_since_sending = (datetime.utcnow() - datetime.strptime(created_at_no_tz, '%Y-%m-%dT%H:%M:%S.%f')).seconds
     if notification["status"] in FAILURE_STATUSES or (
-        notification["status"] in SENDING_STATUSES and seconds_since_sending > 45
+        notification["status"] in SENDING_STATUSES and
+        seconds_since_sending > current_app.config['REPLY_TO_EMAIL_ADDRESS_VALIDATION_TIMEOUT']
     ):
         verification_status = "failure"
         form.email_address.data = notification['to']