Browse HTML file source into the message edit box (choose the HTML message type first). You have to make HTML file for example Macromedia DreamWeaver, Pagemill or Notepad first.
MMM lets you "import" plain-text files only. Microsoft Excel spreadsheet is a binary file actualy that can not be imported into MMM directly. However you can easily convert it into a plain-text file by using the File - SaveAs command from the main menu of Microsoft Excel. After you open the Save dialog box in Microsoft Excel, you should select the Save as type as Text (Comma delimited text), enter the file name then click the Save button. When the plain-text file is ready, all you need to do this to open NotePad, select all and copy text to clipboard. Go to MMM and paste (Ctrl+V) above "List of emails to send" memo.
Port number: The port number of outgoing SMTP relay server. If you check "Use built-in SMTP server" checkbox, it starts SMTP server, which searches free ports from 30 port number. Therefore you must set - for example in Outlook Express - 30 port number instead of 25. It is usually free.
MMM is used by tray bar program too: File menu -> Select "Show in system tray". It resides in the lower right corner of your screen. You can open a main window and then when you close the window, the program minimizes to tray bar automatically. To exit the program, either choose the Exit option from drop down menu on the tray bar icon.
If you select this SMTP relay server, it search email DNS MX records and giving back email's ISP. Some e-mail address can not get mail server correctly. If you use relay server.smt, you couldn't get wrong answer, always send back 'succesful'. If you send the mail and recipient don't get it, it is something wrong on DNS relay server. See free Resolving Name Server homepage what I use in program.