Have you ever noticed that you cannot send any executable file format through mail?
Whatever mail agent would be, say Gmail or Yahoo or Rediff. No one allows you to send files which have executable format like .chm, .exe, .js, .vbs etc

But there are two most common ways to send such files through your mail id. I would show it using Gmail Account.

Problem:  While attaching above mentioned formats, I got error stating that it’s an executable file. For Security reason Gmail doesn’t allow you to send this type of file.

Solution:  There are two methods to bypass this security issue.

Method 1

Steps Included

• Rename the file’s extension  to most common extension which will not cause any security issues.  “txt” or “doc” or “pdf” would be the most useful extension to send executable files.
  For ex: If file name is testing.exe Change it to testing.txt
• Now attach this converted file to your mail id and send. (Gmail would not show any error with such files)
• Tell the recipient that after downloading that attached file change it to proper file extension. In this case, change it from testing.txt to testing.exe
• Done! (It shows that Gmail only checks the file extension not the contents inside it. Even it is not checking for signature/pattern to determine whether it is proper file or not. )

Method 2

Problem: Method 1 would work if you have to single file or separate files in the same mail but by attaching one by one separately. What if you have lots of files of same or different extensions which you want to sent as a whole. Rather say you want to send a folder containing various executable files. 

Solution: We can send it through any compressing tool which has the feature to set password to your file or folder. Winrar being the best example for this scenario. Download it from the here

Steps Included:

• Right click on the file or folder that you want to send and click on add to archive option
• Set the password
  • Click on Advanced tab 
  • Now click on set Password button (see at the right center )
  • Type the password and reconfirm it again.
  • Click Ok
  • Again click Ok to get out of making rar file.
• Now you will see one new file with .rar extensions. Ex: If you have file called abc.chm or a folder called setup which is have lots of executables files inside. Then after doing above steps, you would get abc.chm.rar or folder-name.rar.
• Attach that file in your Gmail account and send to the specific user.(Maximum file size allowed by Gmail per mail is 25 MB)
• Done! It shows that It checks the files and contents inside it but cannot scan the files which is password protected. So it simply allows it!

If you know any other way to send such files, please do comment. I tested it on Gmail but I think it would work in almost all mail clients.