Hi, to use EASendMail in SSIS, you need to install it to Global Assembly Cache at first:

Install EASendMail SMTP Component to Global Assembly Cache - SSIS

For SQL Server Integration Services (SSIS) or other .NET integrated script platform, it requires external DLL to be installed into .NET Global Assembly Cache. You can install EASendMail to Global Assembly Cache like this:

If you have Visual Studio installed on your computer: On the taskbar, click Start, click All Programs, click Visual Studio, click Visual Studio Tools, and then click Visual Studio Command Prompt. - For Windows Vista or later OS, Please right-click and click "Run As Administrator".

-or-

If you have the Windows SDK installed on your computer: On the taskbar, click Start, click All Programs, click the folder for the Windows SDK, and then click Command Prompt (or CMD Shell). - For Windows Vista or later OS, Please right-click and click "Run As Administrator".

At the command prompt, type the following: (Please change C:\Program Files (x86)\EASendMail to EASendMail installation path, and change EASendMail35.dll to the DLL that you refered in your project.)

gacutil /i "C:\Program Files (x86)\EASendMail\EASendMail35.dll"

Press enter, EASendMail35 will be installed to .NET framework 3.5 Global Assembly Cache.

To uninstall it from Global Assembly Cache, type the following:

gacutil /u "EASendMail35"

you should also install EASendMail20.dll, EASendMail40.dll and EASendMail45.dll

Then you can add references by menu->Projects->References-Imported Namespace.