52.184.164.73 in my logs

[daniel_1983 at protonmail.com]

Dear list,

One of my users is reading e-mail from his phone. When he logs in, this is what I see in my logs : 

Apr 10 16:17:58 auth-worker(17101): Debug: sql(xxx at mydomain.tld,52.184.164.73): query: SELECT email as user, password FROM users WHERE email = LOWER('xxx at mydomain.tld')
[...]
Apr 10 16:17:58 imap-login: Info: Login: user=<xxx at mydomain.tld>, method=LOGIN, rip=52.184.164.73, lip=10.10.10.19, mpid=19286, TLS, session=<E6cEB4BprgA0uKRJ>



Both lines show a remote IP of 52.184.164.73, which is strange since all my users are, and connect from, Algeria. According to the ispinfo website (http://www.ispinfo.net/isp/52.184.164.73.html), this IP belongs to Microsoft.

Could it be that the outlook app uses microsoft's servers to fetch the mail before handing them to the user ? 

Daniel.