Eu nunca usei blat, mas usei o bmail . É muito simples, pequeno (17kb) e pode ser facilmente usado em scripts em lote.
C:\>bmail /?
Command Line SMTP Emailer V1.07
Copyright(C) 2002-2004 [email protected]
Usage: bmail [options]
-s SMTP Server Name
-p SMTP Port Number (optional, defaults to 25)
-t To: Address
-f From: Address
-b Text Body of Message (optional)
-h Generate Headers
-a Subject (optional)
-m Filename (optional) Use file as Body of Message
-c Prefix above file with CR/LF to separate body from header
-d Debug (Show all mail server communications)
o bmail é freeware.