This is a very small and trivial piece of software but is has really helped me so many times that I thought I would share it.
All it does is provide a friendly User Interface via which you can quickly set the properties of an SMTP server, a sender, some recipients and an email body for transmission. It then attempts to send the email and informs of the outcome. It helps a lot in situations when you need to check connectivity/firewall issues, to see why some of your emails don't get delivered to a server or even for testing while authoring a Newsletter template and need to send multiple times to many different services.
Please feel free to download and use!