Good Alternatives to Blat

You could try bmail, a free, lean command line SMTP mail sender for Win32 platforms. With the also free available utility mpack you can use bmail to send mime attachments.

Usage and options:

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)

Update:

Another alternative is cmdsendmail, one of the "CommandLine Tools" (open source, hosted on CodePlex.com):

cmdsendmail is a tool that allows to send e-Mail from your Command Line. It reads it’s settings from an Xml file, which means you can easily use it in a Batch File. For example, include it in your Backup scripts (or any other scheduled task) and have the script send an e-Mail to you whenever the backup task is finished, with the neccessary Logfiles attached.