Sometimes you receive PDF attachments which are not printed correctly, this problem is due to a PDF not fully compliant with standard, generally there is an error in the header of the file, even if it can be opened by other email reader like Adobe Acrobat or Foxit reader.

Note: You can use a free online service to test your PDF file, like this one: https://www.pdf-online.com/osa/validate.aspx

Here 2 solutions for this problem

First one, you contact the owner of the PDF file, and you ask him to update the PDF generator or use another one.

The second solution is to not use the internal system of Automatic Email Manager to print PDF, but an external program like free Adobe Acrobat reader, free FoxIt Reader,…

Set Automatic Email Manager to use an external program to print PDF:

1. Click left menu ‘Settings’
2. Then click section 'Email attachments' 
3. Click on 'File type management'
4. Search for PDF extension, click on 'Settings'
5. Set to use default program.

Now make sure to have a PDF reader installed like Adobe Acrobat reader or Foxit reader.

This solution works fine only if you run Automatic Email Manager under a Windows session, if you run Automatic Email Manager in service mode (without any user logged) then it will not work.