it should work this way. MIME-13 is implemented completely. I hope so. Now... let's test it! :-D

src/attachment.cc

@@ -91,13 +91,13 @@ void Attachment::write_mime_headers(std::string& out) const
 }
 
 
-SAttachments parse_attachments(const bloblist_t* b)
+SAttachments parse_attachments(const bloblist_t* b, bool has_pEp_msg_attachment)
 {
     unsigned nr_in_bloblist = 0;
     SAttachments ret;
     while(b)
     {
-        ret.emplace_back(b, nr_in_bloblist);
+        ret.emplace_back(b, nr_in_bloblist, has_pEp_msg_attachment);
         b = b->next;
         ++nr_in_bloblist;
     }

src/attachment.hh

@@ -17,27 +17,30 @@ namespace pEpMIME
     // refers to data in a bloblist_t. Does NOT any data!
     struct Attachment
     {
-        explicit Attachment(const bloblist_t* b, unsigned nr_in_bloblist)
+        explicit Attachment(const bloblist_t* b, unsigned nr_in_bloblist, bool has_pEp_msg_attachment)
         : data{b->size ? sv{b->value, b->size} : sv{}}
         , mime_type{b->mime_type}
         , filename{exists(b->filename) ? b->filename : sv{}}
         , dtype{b->disposition}
         , need_te{need_transport_encoding(data)}
-        , nr{nr_in_bloblist}
         {
             if(::pEpMIME::is_inline(b))
             {
                 dtype = PEP_CONTENT_DISP_INLINE;
             }
+            
+            if((mime_type=="message/rfc822") && (nr_in_bloblist==0) && has_pEp_msg_attachment)
+            {
+                mime_type += "; forwarded=\"no\"";
+            }
         }
         
-        Attachment(sv _data, sv _mime_type, unsigned nr_in_bloblist)
+        Attachment(sv _data, sv _mime_type)
         : data{_data}
         , mime_type{_mime_type}
         , filename{}
         , dtype{ PEP_CONTENT_DISP_OTHER }
         , need_te{ need_transport_encoding(data) }
-        , nr{ nr_in_bloblist }
         { }
         
         
@@ -49,16 +52,15 @@ namespace pEpMIME
         }
         
         sv data;
-        sv mime_type;
+        std::string mime_type;
         sv filename;
         content_disposition_type dtype;
         bool need_te; // need transport encoding
-        unsigned nr;
     };
     
     typedef std::vector<Attachment> SAttachments;
     
-    SAttachments parse_attachments(const bloblist_t* att);
+    SAttachments parse_attachments(const bloblist_t* att, bool has_pEp_msg_attachment);
     
     inline
     bool all(const Attachment&) { return true; }

src/bodygenerator.cc

@@ -101,7 +101,7 @@ void generate_ma_body(std::string& smsg, sv plain_mimetype, sv plain, sv html)
 void generate_mm_body(std::string& smsg, sv mime_type, sv body, const std::vector<Attachment>& a)
 {
     std::vector<Attachment> a2{a};
-    a2.emplace_back(body, mime_type, a2.size());
+    a2.emplace_back(body, mime_type);
     
     const std::string delimiter = create_delimiter(a2);
     
@@ -126,10 +126,10 @@ void generate_complex_body(std::string& smsg, unsigned det, const message* msg,
 
     std::vector<Attachment> a2{a};
     if(msg->longmsg)
-        a2.emplace_back(msg->longmsg, longmsg_mimetype, a2.size());
+        a2.emplace_back(msg->longmsg, longmsg_mimetype);
     
     if(msg->longmsg_formatted)
-        a2.emplace_back(msg->longmsg_formatted, "text/html", a2.size());
+        a2.emplace_back(msg->longmsg_formatted, "text/html");
     
     // basic delimiter:
     const std::string delimiter = create_delimiter(a2) + "/" + std::to_string(det) + "/";

src/pEpMIME.cc

@@ -220,7 +220,7 @@ char* generate_message(const message* msg_orig, bool omit_fields, bool has_pEp_m
         msg.add_header(Pseudo_Header_Forwarded, "no");
     }
     
-    const auto attachments = parse_attachments(msg->attachments);
+    const auto attachments = parse_attachments(msg->attachments, has_pEp_msg_attachment);
     const unsigned inline_attachments = std::count_if(
             attachments.cbegin(), attachments.cend(),
             [](const Attachment& a) { return a.is_inline(); }