Evaluate email using INDY 10 and Delphi

function LinesFromMsg(aMsg: TIdMessage): TStrings; 
var
 i: Integer; 
begin
 for i := 0 to aMsg.MessageParts.AttachmentCount-1 do< br /> begin
 if (amsg.MessageParts.Items[i].ContentType ='HTML') then
 begin
 if (amsg.MessageParts.Items[i] is Tidtext) then< br /> Result := TidText(amsg.MessageParts.Items[i]).body;
 end;
 end; 
end;

function HTMLFromMsg(aMsg: TIdMessage): TStrings; 
var
 i: Integer; 
 Part: TIdMessagePart;
begin
 Result := nil;< br /> if IsHeaderMediaType(aMsg.ContentType,'text/html') then
 begin
 Result := aMsg.Body;
 Exit;
 end;
 for i := 0 to aMsg.MessageParts.Count-1 do
 begin
 Part := aMsg.MessageParts.Items[i];
 if (Part is TIdText) and IsHeaderMediaType(Part.ContentType ,'text/html') then
 begin
 Result := TIdText(Part).Body;
 Exit;
 end;
 end; 
end ;

procedure DisplayPlainText(Body: TStrings);
begin
 // display plain text as needed...
end;

procedure DisplayHTML(Body: TStrings);
begin
 // display html as needed...
end; 

procedure DisplayMultiPartAlternative(aMsg: TIdMessage; aParentIndex, aLastIndex: Integer);
var
 Part: TIdMessagePart;
 i: Integer:
begin
 for i := aLastIndex-1 downto aParentIndex+1 do
 begin
 Part := aMsg.MessageParts.Items[i];
 if (Part.ParentPart = aParentIndex) and (Part is TIdText) then
 begin
 if IsHeaderMediaType(Part.ContentType,'text/html') then
 begin
 DisplayHTML(TIdText(Part).Body);
 Exit;
 end;
 if IsHeaderMediaType(Part.ContentType,'text/plain') then
 begin
 DisplayPlain(TIdText(Part).Body);
 Exit;
 end;
 end;
 end;
 // nothing supported to display...
end;

procedure DisplayMultiPartMixed( aMsg: TIdMessage; aParentIndex, aLastIndex: Integer);
var
 Part: TIdMessagePart;
 i: Integer;
begin
 for i := aLastIndex-1 downto aParentIndex +1 do
 begin
 Part := aMsg.MessageParts.Items[i];
 if (Part.ParentPart = aParentIndex) and (Part is TIdText) then
 begin
 if IsHeaderMediaType(Part.ContentType,'multipart/alternative') then
 begin
 DisplayMultiPartAlternative(aMsg, ParentPart.Index, aLastIndex);
 Exit;
 end;
 if IsHeaderMediaType(ParentPart.ContentType,'text/html') then
 begin
 DisplayHTML(TIdText(Part).Body);
 Exit;
 end;
 if IsHeaderMediaType(Part.ContentType,'text/plain') then
 begin
 DisplayHTML(TIdText(Part).Body);
 E xit;
 end;
 aLastIndex := i;
 end;
 // nothing supported to display...
 end;

 
procedure DisplayMsg(aMsg: TIdMessage); 
var
 ContentType: string;
begin
 ContentType := ExtractHeaderMediaType(aMsg.ContentType);
 case PosInStrArray (ContentType, ['multipart/mixed','multipart/alternative','text/html','text/plain'], False) of
 0: begin
 DisplayMultiPartAlternative(aMsg, -1, aMsg.MessageParts.Count);
 Exit;
 end;
 1: begin
 DisplayMultiPartMixed(aMsg, -1, aMsg.MessageParts.Count);
 Exit; 
 end;
 2: begin
 DisplayHTML(aMsg.Body);
 Exit;
 end;
 3: begin
 DisplayPlainText(aMsg .Body);
 Exit;
 end;
 else
 // nothing supported to display...
 end;
end;

I use the following code to evaluate msg. The content (body/line) of the E Mail message received using the INDY 10 component

function L inesFromMsg(aMsg: TIdMessage): TStrings; 
var
 i: Integer; 
begin
 for i := 0 to aMsg.MessageParts.AttachmentCount-1 do
 begin 
 if (amsg.MessageParts.Items[i].ContentType ='HTML') then
 begin
 if (amsg.MessageParts.Items[i] is Tidtext) then
 Result := TidText(amsg.MessageParts.Items[i]).body;
 end;
 end; 
end;

I have two questions about this code :

a) Is this the correct way to find the Tlines part in the arbitration email?
(Consider the recommendations shown in INDY 10 EMAIL MSG PARTS)

b) Where can I find tutorials for all the different Contenttype string values?

The correct ContentType value to find is text/html. Use Indy’s IsHeaderMediaType() function to check, because the ContentType value may have a comparison with yours and need to be ignored

You also need to consider TIdMessage.ContentType, because HTML emails may not be MIME-encoded, so the TIdMessage.MessageParts` collection is not used at all.

Finally, the loop needs to use the MessageParts.Count property instead of the MessageParts.AttachmentsCount property.

Try this:

function HTMLFromMsg(aMsg: TIdMessage): TStrings; 
var
 i: Integer; 
 Part: TIdMessagePart;
begin
 Result := nil;
 if IsHeaderMediaType(aMsg.ContentType,'text /html') then
 begin
 Result := aMsg.Body;
 Exit;
 end;
 for i := 0 to aMsg.MessageParts.Count-1 do
 begin
 Part := aMsg.MessageParts.Items[i];
 if (Part is TIdText) and IsHeaderMediaType(Part.ContentType,'text/html') then
 begin
 Result := TIdText(Part).Body;
 Exit;
 end;
 end; 
end;

That said, Technically, this is not the correct way to deal with MIME. Formally, standard-compliant readers should loop backward through the MIME parts as they sort down from the simplest form to the most complex form. Therefore, you need to After the loop, the MIM E nesting considerations, look for the most complex form you support. Something more like this (untested):

procedure DisplayPlainText(Body: TStrings);< br />begin
 // display plain text as needed...
end;

procedure DisplayHTML(Body: TStrings);
begin
 / / display html as needed...
end;

procedure DisplayMultiPartAlternative(aMsg: TIdMessage; aParentIndex, aLastIndex: Integer);
var
 Part: TIdMessagePart;< br /> i: Integer:
begin
 for i := aLastIndex-1 downto aParentIndex+1 do
 begin
 Part := aMsg.MessageParts.Items[i];< br /> if (Part.ParentPart = aParentIndex) and (Part is TIdText) then
 begin
 if IsHeaderMediaType(Part.ContentType,'text/html') then
 begin
 DisplayHTML(TIdText(Part).Body);
 Exit;
 end;
 if IsHeaderMediaType(Part.ContentType,'text/plain') then
 begin
 DisplayPlain (TIdText(Part).Body);
 Exit;
 end;
 end;
 end;
 // nothing supported to display...
end;

procedure DisplayMultiPartMixed(aMsg: TIdMessage; aParentIndex, aLastIndex: Integer);
var
 Part: TIdMessagePart;
 i: Integer;
begin
 for i := aLastIndex-1 downto aParentIndex+1 do
 begin
 Part := aMsg.MessageParts.Items[i ];
 if (Part.ParentPart = aParentIndex) and (Part is TIdText) then
 begin
 if IsHeaderMediaType(Part.ContentType,'multipart/alternative') then
 begin< br /> DisplayMultiPartAlternative(aMsg, ParentPart.Index, aLastIndex);
 Exit;
 end;
 if IsHeaderMediaType(ParentPart.ContentType,'text/html') then
 begin< br /> DisplayHTML(TIdText(Part).Body);
 Exit;
 end;
 if IsHeaderMediaType(Part.ContentType,'text/plain') then
 begin
 DisplayHTML(TIdText(Part).Body);
 Exit;
 end;
 aLastIndex := i;
 e nd;
 // nothing supported to display...
 end;


procedure DisplayMsg(aMsg: TIdMessage); 
var
 ContentType: string;
begin
 ContentType := ExtractHeaderMediaType(aMsg.ContentType);
 case PosInStrArray(ContentType, ['multipart/mixed','multipart/alternative','text/html' ,'text/plain'], False) of
 0: begin
 DisplayMultiPartAlternative(aMsg, -1, aMsg.MessageParts.Count);
 Exit;
 end;
 1: begin
 DisplayMultiPartMixed(aMsg, -1, aMsg.MessageParts.Count);
 Exit;
 end;
 2: begin
 DisplayHTML(aMsg. Body);
 Exit;
 end;
 3: begin
 DisplayPlainText(aMsg.Body);
 Exit;
 end;
 else 
 // nothing supported to display...
 end;
end;