diff --git a/Core/Executor/MailExecutor.php b/Core/Executor/MailExecutor.php
index 1fa80e50..bdd8d4ba 100644
--- a/Core/Executor/MailExecutor.php
+++ b/Core/Executor/MailExecutor.php
@@ -74,8 +74,14 @@ protected function send($dsl, $context)
         if (isset($dsl['body'])) {
             $message->setBody($this->resolveReferencesInText($dsl['body']));
         }
-        if (isset($dsl['attach'])) { /// @todo
-            $message->attach(Swift_Attachment::fromPath($this->resolveReferencesRecursively($dsl['attach'])));
+        if (isset($dsl['attach'])) {
+            $path = $this->resolveReferencesRecursively($dsl['attach']);
+            // we use the same logic as for the image/file fields in content: look up file 1st relative to the migration
+            $attachment = dirname($context['path']) . '/' . $path;
+            if (!is_file($attachment)) {
+                $attachment = $path;
+            }
+            $message->attach(Swift_Attachment::fromPath($attachment));
         }
 
         if (isset($dsl['priority'])) {
diff --git a/Core/Executor/ReferenceExecutor.php b/Core/Executor/ReferenceExecutor.php
index d81e2e84..19aebddb 100644
--- a/Core/Executor/ReferenceExecutor.php
+++ b/Core/Executor/ReferenceExecutor.php
@@ -56,8 +56,9 @@ protected function set($dsl, $context)
             throw new \Exception("Invalid step definition: miss 'value' for setting reference");
         }
         $value = $dsl['value'];
-        if (preg_match('/%.+%$/', $value)) {
-            $value = $this->container->getParameter(trim($value, '%'));
+        if (preg_match('/.*%.+%.*$/', $value)) {
+            // we use the same parameter resolving rule as symfony, even though this means abusing the ContainerInterface
+            $value = $this->container->getParameterBag()->resolveString($value);
         }
         $overwrite = isset($dsl['overwrite']) ? $overwrite = $dsl['overwrite'] : false;
         $this->referenceResolver->addReference($dsl['identifier'], $value, $overwrite);
diff --git a/Tests/dsl/bad/parsing/UnitTestKO011_invalid_json.json b/Tests/dsl/bad/parsing/UnitTestKO012_invalid_json.json
similarity index 100%
rename from Tests/dsl/bad/parsing/UnitTestKO011_invalid_json.json
rename to Tests/dsl/bad/parsing/UnitTestKO012_invalid_json.json
diff --git a/Tests/dsl/bad/parsing/UnitTestKO012_wrong_json.json b/Tests/dsl/bad/parsing/UnitTestKO013_wrong_json.json
similarity index 100%
rename from Tests/dsl/bad/parsing/UnitTestKO012_wrong_json.json
rename to Tests/dsl/bad/parsing/UnitTestKO013_wrong_json.json
diff --git a/Tests/dsl/good/UnitTestOK22_file.yml b/Tests/dsl/good/UnitTestOK022_file.yml
similarity index 100%
rename from Tests/dsl/good/UnitTestOK22_file.yml
rename to Tests/dsl/good/UnitTestOK022_file.yml
diff --git a/Tests/dsl/good/UnitTestOK023_mail.yml b/Tests/dsl/good/UnitTestOK023_mail.yml
new file mode 100644
index 00000000..0b6bc8f7
--- /dev/null
+++ b/Tests/dsl/good/UnitTestOK023_mail.yml
@@ -0,0 +1,83 @@
+-
+     type: reference
+     mode: set
+     identifier: kmb_test_023_subject
+     value: testing
+
+-
+     type: reference
+     mode: set
+     identifier: kmb_test_023_body
+     value: migrations
+
+-
+    type: mail
+    mode: send
+    from: test@test.me
+    to: test@test.you
+    cc: test@test.him
+    bcc:
+        - test@test.her
+        - test@test.they
+    subject: "this is an email subject about [reference:kmb_test_023_subject] etc..."
+    body: "this is an email body about [reference:kmb_test_023_body] etc..."
+    attach: files/emptyfile.txt
+
+# NB: this file is made available by a custom swiftmailer listener
+-
+    type: file
+    mode: load
+    file: /tmp/mail.txt
+    references:
+        -
+            attribute: body
+            identifier: kmb_test_023_mailmessage
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "From: test@test.me"
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "To: test@test.you"
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "Cc: test@test.him"
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "Bcc: test@test.her, test@test.they"
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "Content-Type: multipart/mixed;"
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "this is an email body about migrations etc..."
+
+-
+    type: assert
+    target: reference
+    identifier: reference:kmb_test_023_mailmessage
+    test:
+        contains: "Subject: this is an email subject about testing etc..."
diff --git a/Tests/ezpublish/config/config_behat_ezplatform.yml b/Tests/ezpublish/config/config_behat_ezplatform.yml
index 439996ef..52b115a7 100644
--- a/Tests/ezpublish/config/config_behat_ezplatform.yml
+++ b/Tests/ezpublish/config/config_behat_ezplatform.yml
@@ -46,6 +46,7 @@ stash:
             registerDoctrineAdapter: false
 
 swiftmailer:
+    disable_delivery: false
     spool:
         type: file
         path: '%kernel.root_dir%/spool'
diff --git a/Tests/ezpublish/config/config_behat_ezpublish-community.yml b/Tests/ezpublish/config/config_behat_ezpublish-community.yml
index 4c5e2775..e26c3218 100644
--- a/Tests/ezpublish/config/config_behat_ezpublish-community.yml
+++ b/Tests/ezpublish/config/config_behat_ezpublish-community.yml
@@ -31,6 +31,7 @@ ez_publish_legacy:
     root_dir: %kernel.root_dir%/../../ezpublish-legacy
 
 swiftmailer:
+    disable_delivery: false
     spool:
         type: file
         path: '%kernel.root_dir%/spool'
diff --git a/Tests/ezpublish/config/services.yml b/Tests/ezpublish/config/services.yml
index bb77f909..79158b71 100644
--- a/Tests/ezpublish/config/services.yml
+++ b/Tests/ezpublish/config/services.yml
@@ -23,3 +23,7 @@ services:
         class: Kaliop\eZMigrationBundle\Tests\helper\CustomReferenceResolver
         tags:
             - { name: ez_migration_bundle.reference_resolver.customreference }
+    ez_migration_bundle.test.swiftmailer_message_logger:
+        class: Kaliop\eZMigrationBundle\Tests\helper\MailMessageLogger
+        tags:
+            - { name: swiftmailer.default.plugin }
diff --git a/Tests/helper/MailMessageLogger.php b/Tests/helper/MailMessageLogger.php
new file mode 100644
index 00000000..14cc9ae1
--- /dev/null
+++ b/Tests/helper/MailMessageLogger.php
@@ -0,0 +1,19 @@
+<?php
+
+namespace Kaliop\eZMigrationBundle\Tests\helper;
+
+use Swift_Plugins_MessageLogger;
+use Swift_Events_SendEvent;
+
+class MailMessageLogger extends Swift_Plugins_MessageLogger
+{
+    /**
+     * @todo make the name of the written file configurable, and/or do set references to it on saving
+     * @param Swift_Events_SendEvent $evt
+     */
+    public function sendPerformed(Swift_Events_SendEvent $evt)
+    {
+        $msg = $evt->getMessage();
+        file_put_contents('/tmp/mail.txt', $msg->toString());
+    }
+}
diff --git a/WHATSNEW.md b/WHATSNEW.md
index 66195be3..a964c319 100644
--- a/WHATSNEW.md
+++ b/WHATSNEW.md
@@ -3,6 +3,10 @@ Version 4.0
 
 * New: allow to set references to contentType default_always_available, default_sort_field, default_sort_order, is_container
 
+* Improved: parameter resolving in migration steps reference/set now works even when the parameter is not the full value of the string, eg: '%kernel.root_dir%/spool'
+
+* Improved: path to attachment files can be specified relative to the migration file for migration steps mail/send
+
 
 Version 4.0 RC-5
 ================