Use Thunderbird (widely used open software) as your e-mail application in the following way:
I suggest that you get a web mail account such as from GMAIL for your official e-mail address (or other web-mail provider, if you don't want Google reading your e-mail). You can then direct all e-mail received by GMAIL to the e-mail account that you have through your Internet provider. (You normally make these adjustments from your web-mail website, if the web-mail that you have chosen has that capability, as GMAIL does.) Possibly, in both cases, your e-mail will be checked for viruses and malware.
Thunderbird can be setup to download your e-mail from your e-mail account that you have through your Internet provider. Thunderbird may be less likely to have security problems than applications such as Outlook or Outlook Express. Set Thunderbird as your PREFERRED e-mail application. For Ubuntu Linux use this menu selection: System → Preferences → Preferred Applications. A window will open up, and then click on the Internet tab along the top panel of the window. Use the drop-down list to select Mozilla Thunderbird as your preferred mail reader.
When you run the Thunderbird e-mail program, also make this adjustment from its menu selection: Edit → Preferences → Security → Web Content. On the "Web Content" window make the adjustment to "Accept cookies from sites" until "I close Thunderbird" so that all your cookies will be deleted every time you close Thunderbird.
Among Thunderbird's security features are functions such as disallowing pictures from being downloaded from the Internet without your permission. In this way it gives you added privacy and protection from organizations sending “spam” mail, because if the pictures are not downloaded, the “spammers” cannot verify that your address is a real viable address. If they think it is an “inactive” address, they may remove it from their database of addresses that they use to send their spam mail or which they use to sell to other spammers. Besides this, Thunderbird has a powerful feature that you can customize (and make it “learn”) to automatically detect spam mail.