[quote user="Joerg"]The error message itself is OK in case Pmail / IER detects a wrong file format. But why it appears so often?[/quote]

Here we go again, Joerg: Since you describe this error message twice as occuring while replying it can't be an IER error message, and I'm 100% sure it's a TER/HTS error message since I've seen such error messages before. There are further indicators confirming this: IER's own error messages would usually come with a caption showing IER's name and version number as their title - if they don't come as an exception dialog which usually includes the exception code and address. Errors only affecting replies, forwards or printing are usually TER/HTS errors, only so-called runtime errors and exceptions might come from other modules except when clearly indicated as IER error messages as explained above.

Now with regard to fixing such an error: No chance except for buying a more recent TER/HTS version by David Harris as discussed in a recent thread. I do already fix such errors by decoding and recoding faulty PNG files when they come as embedded images within the HTML message (it's possible to do this), but if they come as attached parts in a multipart/related MIME message the images aren't submitted to the HTML renderers for fixing prior to Pegasus Mail's reply, forward or print processing with TER/HTS.

Sorry to say (and not to know why this dialog shows up more than once) ...

FYI:

Today we received an email which contained, due to different reply actions, 15 attached images (jpg and png mixed). Now, one colleague tried to answer again but his reply attempt leads to an error message "Invalid File Format" which he claimed with me. I've checked the different attached image files and found out that one png file has a fault extension. It was a bmp file but not a png.

But the remarkable thing is, that Pmail / IER created the error message 18 times, which all have to be confirmed firstly before the reply could be composed. My colleague has already gave up and said Pmail is hanging. I had more patience and after 18 times of error confirmation Pmail proceeded.

The error message itself is OK in case Pmail / IER detects a wrong file format. But why it appears so often?

Joerg,    The problem may be that the "PNG" file may be a zipped PNG with Header bytes x'1F' +  x'8B' rather than normal 'P' and 'N'. This zipped file needs Gzip to unpack it.  Zipped PNG files became necessary when large images were being created. PNG is a text based file structure.  BMP files have header bytes 'B' + 'M'.

I think someone had a default image type set as BMP. If the attachment had no extension, just the name, IE or IERenderer are probably guessing at a file type. In Bearhtml, I always examine the header signatures and if there is no file extension, I always convert the file to a known type such as Jpg. 

Martin 

I don't know whether it was a zipped png or what kind of headers are used. But a simple freeware image viewer (Irvan View) told me that it is a bmp instead of a png. That's why I renamed it from png to bmp and could view the image. ... But this is not the point for me. Wrong files could appear in the internet.

I was a little bit confused about the number of identical error messages which a user has to confirm until Pmail poceeds.