Feature: add support for emailing multiple documents (#10666)

---------

Co-authored-by: shamoon <4887959+shamoon@users.noreply.github.com>

src/documents/mail.py

@@ -10,11 +10,20 @@ def send_email(
     subject: str,
     body: str,
     to: list[str],
-    attachment: Path | None = None,
-    attachment_mime_type: str | None = None,
+    attachments: list[tuple[Path, str]],
 ) -> int:
     """
-    Send an email with an optional attachment.
+    Send an email with attachments.
+
+    Args:
+        subject: Email subject
+        body: Email body text
+        to: List of recipient email addresses
+        attachments: List of (path, mime_type) tuples for attachments (the list may be empty)
+
+    Returns:
+        Number of emails sent
+
     TODO: re-evaluate this pending https://code.djangoproject.com/ticket/35581 / https://github.com/django/django/pull/18966
     """
     email = EmailMessage(
@@ -22,17 +31,20 @@ def send_email(
         body=body,
         to=to,
     )
-    if attachment:
-        # Something could be renaming the file concurrently so it can't be attached
-        with FileLock(settings.MEDIA_LOCK), attachment.open("rb") as f:
-            content = f.read()
-            if attachment_mime_type == "message/rfc822":
-                # See https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981
-                content = message_from_bytes(f.read())
 
-            email.attach(
-                filename=attachment.name,
-                content=content,
-                mimetype=attachment_mime_type,
-            )
+    # Something could be renaming the file concurrently so it can't be attached
+    with FileLock(settings.MEDIA_LOCK):
+        for attachment_path, mime_type in attachments:
+            with attachment_path.open("rb") as f:
+                content = f.read()
+                if mime_type == "message/rfc822":
+                    # See https://forum.djangoproject.com/t/using-emailmessage-with-an-attached-email-file-crashes-due-to-non-ascii/37981
+                    content = message_from_bytes(content)
+
+                email.attach(
+                    filename=attachment_path.name,
+                    content=content,
+                    mimetype=mime_type,
+                )
+
     return email.send()