In SharePoint 2013, when the document library is configured to receive incoming emails, the email attachments sent to document library should be saved as files. When files with same names received, the files should be saved with unique names.
The files with same names are being dropped by (may be) SharePoint timer services. If the file with the name already exists in the document library, the newer file will not be saved.
The issue is when we send multiple files through email at the same time, some of the files are getting dropped.
This issue is the SharePoint 2013.
Regards,
Kunal Mittal