Use a mail client such as Thunderbird rather than web mail readers or the pathetic Outlook.

Thunderbird does not display remote content without asking you. If you receive a message so formatted from a trusted source, you can temporarily switch settings to display it. You can also set it up to ask you before sending message receipts.

Pre- screen your mail with Mailwasher so that the spammers don't even get as far as your mail client.