E-mail security settings

I feel as though all of the following e-mail settings are just as important as the other and I will be looking for these types of security settings within my email client.

Read e-mail messages using a reading pane:        Allows you to read an e-mail message without actually opening it. Even though you can read the e-mail without opening the actual e-mail document you should still be aware of messages and attachments from unknown senders.

Block external content:    Prevents the user's computer from downloading the images and external links that are present in an e-mail. Spammers use the external content to note which e-mail addresses are actually in use, allowing them to add the e-mail address to their spam list, they can then sale your e-mail address to other spammers.

Preview attachments:    Some e-mail clients will allow a user to preview an attachment without saving it or opening it. To preview the attachment, the user must have the required application installed in order to view the attachment.     For example: You must have Microsoft Word installed on your computer in order to view an attachment that is a Microsoft Word attachment.

Use an e-mail postmark:    Some e-mail clients will allow for a legit e-mail that could otherwise look as if it were a spam e-mail, to have a postmark into the e-mails header, this postmark can be read by compatible e-mail clients on the receiving end. The compatible e-mail client will recognize the postmark and allow it thru.

I use the e-mail that is provided from my user account at peoplestring.com.
I will now examine my e-mail security settings within my peoplestring e-mail:

My e-mail client does offer a preview pane; it offers to hide or display remote inline images (block external content) and allows you to hide or display attached images below the message.
You can adjust the Score threshold. If you choose 1-3, this is the highest setting. (By selecting the highest setting you may miss a few real emails as it could result in them being marked as Spam.) A medium Spam setting would be in the 4-6 range, and low would be 7 or higher. You can adjust these settings according to your preferences. You can also choose a setting to allow or disallow e-mails sent in certain languages. Peoplestring e-mail allows you to set certain address rules; to allow or reject certain email addresses. I have set up to reject a few different e-mail addresses that I have received daily spam emails from yet I still receive them, the spam showed into my inbox daily until I set my score threshold, now it goes into my junk folder.

I did not see any settings for allowing an e-mail postmark so I will give the peoplestring e-mail a security ranking of 3 out of 5.

I will now check my wife's e-mail client G-mail from Google.
Her G-mail account allows for security settings such as allow or disallow external content such as view images. I advised her and changed her setting to disallow the external content.
G-mail allows users to view a snippet of the message (like Google web search!) in my opinion it does not show enough of a preview to make me feel secure.
I did not see anything available to allow for her to preview attachments or create an e-mail postmarks.
I did not see the opportunity to setup and adjust a score threshold like is available at peoplestring.com.
I will give G-mail a security ranking of only 2 out of 5.
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As for me I am going to check into setting up a Microsoft Outlook account, since I have it already installed on my computer. I will do this to see if I can get a better security ranking from Outlook. I have seen Outlook quoted several times in my Security Awareness book that I am learning from in college.