Hi @JulienC,
Unless your Mattermost instance is located in Dubai, that shouldn't be caused by Mattermost itself.
The only place that Mattermost uses your credentials is when connecting to the email server to send messages. The SMTP server, port, and username are also made available to admins in the System Console, but the password isn't sent to the client so unless someone had direct access to the config files, no users could get access to all of the credentials required to send emails.