When attaching PDF v1.7 to an email in Outlook, it's sent as:
Content-Type: application/pdf; Content-Transfer-Encoding: quoted-printable
When receiving such an e-mail under Linux (Thunderbird), the PDF content is being parsed as a plain text and converted. This results in a corrupted file loosing all the bytes 0x0a (LF) which are being removed by the EOL conversion.
On the contrast, when attaching an older PDF (like v1.3) to an email in Outlook, it's sent correctly as:
Content-Type: application/pdf; Content-Transfer-Encoding: base64
which is received and decoded correctly.
It's definitely a problem of Outlook (don't know which version, probably up to MSO 2007 - just guessing, since v1.7 of PDF has become ISO standard in 2008).
I'm not the creator nor the sender of those attachments! Our company is just suffering from that issue while receiving hundreds of PDFs each day sent by people from outside. We can not force all the senders to place the PDFs in an archive or to fix it on their side.
I want to ask if somebody has been facing this and if there is a way how to force Thunderbird to bypass the plain-text EOL conversion when Content-Type is "application/pdf", or something like that to workaround the problem on the receiver side.