Man-in-the-middle (MITM): Email clients

How are the most popular email clients connecting? Direct or indirect with a client/server in between? Should one be in between, there is a man-in-the-middle!

What is a man-in-the-middle?


When we search for ‘man-in-the-middle’ in the search engines, we always find the term ‘man-in-the-middle attack‘. Why always think so negative and assume from an attack? Let’s ask: Is a man-in-the-middle welcomed or an attack present?

According to Wiki a man-in-the-middle attack (MITM) is an attack where the attacker secretly relays and possibly alters the communication between two parties who believe they are directly communicating with each other.

Tests and results

We tested the ten most popular desktop email clients, whether they connect directly or indirectly (MITM) to our email server (

(Tests are performed with current OS and email client versions from Sat, August 11th, 2018.)


All tested e-mail clients have established a direct connection to our email server as expected thank’s to DNSSEC* and DANE implementation. We refer to ‘How to enable TLS v1.1 and v1.2 in Outlook on Windows 7‘ for those who are using older software versions.

*) DNSSEC video by F5 Networks’ DevCentral community the place to get answers, share solutions, learn F5 technology and stay connected with F5 experts. Join the community here:

Liability disclaimer

The information presented on these pages are not intended to be regarded as legally binding. Since pages published on the internet are often changed, the contents, representations and images/videos must be evaluated as found. Jaispirit Co., Ltd. assumes no liability for any possible damages, loss of earnings or other economic losses incurred as a result of the information, texts or contexts presented on these pages.

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