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.