Attachments are show as text on the email's body form printers and smart phones only

When we send any attachment from a printer o a smart phone (iPhone / android) the attachment appears as text on the e-mail and not like an attachment. This happen after an upgrade from Zimbra Network 7.2 to 8.0

Example:

Content-Type: application/pdf; name="20121031072404433.pdf"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
filename="20121031072404433.pdf"

JVBERi0xLjQKJRamipIKNCAwIG9iago8PC9UeXBlL1hPYmplY3 QKL1N1YnR5cGUvSW1hZ2UK
L1dpZHRoIDE3MDQKL0hlaWdodCAyMjAwCi9CaXRzUGVyQ29tcG 9uZW50IDEKL0NvbG9yU3Bh
etc.

Any suggestion to fix this issue?

Thank you,