We have had some users reporting that some outbound emails with attachments (Pdf, word docs) are not being received by the recipient. Internal and external recipients both.  Looking at mail tracking for those messages the attachments are not hitting the Exchange server.  

We have Exchange 2010 sp3 ,  the users who are having the issue all use Outlook 2013.  We have users using Outlook 2007 with no issue.  We no have no outbound filtering for email. 

Not sure if this is an Exchange issue or Outlook.

Thank you.

please check the internet header of the email from where the attachments are missing. we can get some clue from the internet header.

Hi,

By default, Outlook 2013 will block attachments of some certain types.

https://support.office.com/en-za/article/Blocked-attachments-in-Outlook-434752e1-02d3-4e90-9124-8b81e49a8519

Does Outlook 2013 only block attachment of .Pdf and .docx types?

Please try to rename these file name extension to check this issue.

Meanwhile, please login OWA to check this issue.

Best Regards.