Try to reorder parts

mail_embed_image/models/ir_mail_server.py

@@ -6,7 +6,7 @@
 import uuid
 from base64 import b64encode
 from email.mime.image import MIMEImage
-
+from email.mime.multipart import MIMEMultipart
 import requests
 from lxml.html import fromstring, tostring
 
@@ -58,12 +58,39 @@ def build_email(
             subtype_alternative=subtype_alternative,
         )
         if fileparts:
-            for fpart in fileparts:
-                result.attach(fpart)
             # Multipart method MUST be multipart/related for CIDs embedding
             # Gmail and Office won't process the images otherwise
             if image_embedding_method == "cid":
                 result.set_type("multipart/related")
+
+            for fpart in fileparts:
+                result.attach(fpart)
+
+            # after all part where added, we need to reorganize the parts
+            # before reorganisation, the parts are in this shape:
+            # - boundary 1
+            #   - text/plain
+            #   - text/html
+            #   - image/png
+            # After, the parts are in this shape:
+            # - boundary 1
+            #   - multipart/alternative
+            #     - boundary 2
+            #       - text/plain
+            #       - text/html
+            #   - image/png
+
+            # maybe I could user: result.make_alternative() / result.make_related()
+            alternative = MIMEMultipart('alternative')
+            all_parts = [alternative]
+            for part in result.iter_parts():
+                print(part.get_content_type())
+                if part.get_content_type() in ["text/html", "text/plain"]:
+                    alternative.attach(part)
+                else:
+                    all_parts.append(part)
+            result.set_payload(all_parts)
+
         return result
 
     def _build_email_replace_img_src(self, html_body):