==== Required information ====
- iRedMail version (check /etc/iredmail-release):
- Linux/BSD distribution name and version:
- Store mail accounts in which backend (LDAP/MySQL/PGSQL):
- Web server (Apache or Nginx):
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
======== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.8 MARIADB edition.
- Linux/BSD distribution name and version: CentOS Linux release 7.4.1708 (Core)
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Some of the users report that their iPhone cannot show the email message body as attachment.
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The message cannot be displayed because of the way it is formatted. Ask the sender to send it again using a different format or email program.

multpart/mixed
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iPad, Mac, Windows PC or android are working fine, and tried reboot the iPhone also be same.

Anyone have the same problem and know how to fix?

Many thanks.