If you are concerned about some email content then you can choose to view emails in text only format. Normally emails are displayed as formatted HTML with images.

You can change the text display format in the App Settings - Privacy section. View Emails as HTML with imagesView
You can choose which emails will show full formatted HTML and images:
Always This will always show emails with formatted HTML
Known Senders This will show emails with formatted HTML from people you know.
S/MIME Signed Emails with a valid S/MIME signature will show emails with formatted HTML.

When you are viewing an email in text format you can will see a notice message at the top of the email. Tap on 'Show' to show the email message as formatted HTML with images.

You can see a list of remote images and web links for an email in the email details screen before you view the formatted content. View