For example, you have received an image.bmp file in the attachment. The last but the most prominent reason can be that the temporary folder has already stored the same type of file with the same name for 99 times.There has been some corruption in the Outlook PST file.So, in this case, you will not be able to open the attachment. ai file, but you do not have Adobe Illustrator installed on the machine. You do not have the required program installed on your computer.In this case, you can temporarily restrict your anti-virus to prevent Outlook attachments, and the issue will be fixed. Your anti-virus has been blocking the attachments.
Try the automated tool Kernel for Outlook PST Recovery to repair and recover corrupted PST files and save them in DBX, MBOX, MSG, EML, TXT, RTF, HTML, MHTML and PDF formats.