By default a wordpress installation uses a method of sending mail that does not use a mailbox to send the message and does not encrypt the message. Email cannot be confirmed to be end to end secure unless you know the receiving or sending person is using encryption and is set up correctly; you can encrypt mail in the places where you control email so that it is encrypted from the website to the mailbox. If it is your mailbox, and you know that your mail client is set up correctly with encryption, then you have end to end security. If the website is running over SSL and the address starts with https:// (98% of them are now), then a user entering information into a form is also encrypted. So the path from the users browser, through your contact form, from the website to your receiving mailbox is encrypted and cannot be intercepted as plain text.
How do I make the changes
Log into your website and go to Plugins.
Seatch for WP Mail SMTP, locate it and install it. Continue reading Securing mail from your website to a mailbox