I am using COM-compliant language (xBase++) for Win32, and deploying with Installshield. What DLLs do I need to include in the installer? Do I need only to copy EASendMailObj.dll and register it as a COM server on the target machine?

Yes, you are right

1. copy easendmailobj.dll to destination machine. (run-time file of EASendMail ActiveX Object)
2. run "Regsvr32 [path]\easendmailobj.dll" under dos prompt. (register EASendMail ActiveX Object as com object)

Windows x64(AMD64)

For VBScript/ASP application on Windows x64 platform.
For Visual C++, Delphi application compiled to x64 native code.
Please use the dll in EASendMail installation path\x64\easendmailobj.dll (easendmailobj.dll for x64).
For Visual Basic 6.0 application, because it is always 32bit application, so it can work fine without EASendMail ActiveX Object X64 File.

Thanks!

i want to know what is the trial period of ESsendmail object library ?
presently i am using it on
"tryit" license

Registration-free COM with Manifest File

Registration-free COM is a mechanism available on the Microsoft Windows XP (SP2 for .NET-based components) and Microsoft Windows Server 2003 platforms. As the name suggests, the mechanism enables easy (for example, using XCOPY) deployment of COM components to a machine without the need to register them.

With Registration-free COM, you don't have to use "regsvr32" to register the dll as COM object, you also don't need to worry other version of this COM installed on the same machine overwrite your current version.

We strongly recommend that you use Registration-free COM to distribute EASendMail ActiveX Object with your standard exe application. ASP, VBScript or other script application is not suitable with this feature.

Using Manifest File

For standard exe application, you just need to create a manifest file like this: Open notepad or other text editor, copy/paste the following content to the editor.

Then save it as yourappname.exe.manifest. For example, your application exe file is: myproject1.exe, then save it as myproject1.exe.manifest.

Finally, copy myproject1.exe, myproject1.exe.manifest and EASendMailObj.dll to the same folder on target machine, your application can use EASendMail ActiveX Object directly without COM-registration.

To learn more detail, please have a look at:
http://www.emailarchitect.net/easendmail/sdk/?ct=object_reg_a 

The trial period is 30 days.