==== Required information ====
- iRedMail version (check /etc/iredmail-release):
0.9.6 MYSQL edition

- Linux/BSD distribution name and version:
Ubuntu 16.04

- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
MySQL

- Web server (Apache or Nginx):
NginX

- Manage mail accounts with iRedAdmin-Pro?
No

- Related log if you're reporting an issue:
N/A
====

For some weird reason mail stays read on mail.app on IOS. All other applications correctly display the read / unread status.
(Roundcube, Mail.app on MacOS, Spark). I do get new e-mail on IOS, however deleted mail using other applications, also still show & mail app.

Any suggestions? Very weird problem.