==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):  iRedMail-1.6.2
- Deployed with iRedMail Easy or the downloadable installer? downloadable installer
- Linux/BSD distribution name and version: Ubuntu 20.04.3 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): PGSQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

使用iredmail发送和接收邮件时，如果附件中带了exe文件就会被丢弃，应该如何配置iredmail让它不丢弃这种类型的文件呢？或者至少给发送方反馈一个信件被拒收的提示，而不是什么都不知道，让发送方误以为成功发出去了，但是接收方缺没收到，两边都对此毫不知情。

相关日志信息如下：
Feb  6 01:45:11 mail amavis[119044]: (119044-01) Blocked BANNED (.exe,.exe-ms,IS32U512A.exe) {DiscardedInternal,Quarantined}, ORIGINATING/MYNETS LOCAL [127.0.0.1]:56502 ESMTP/ESMTP <*.jia@*.com> -> <*.yang@*.com>, (), quarantine: bBZk6wDpKvRc, Queue-ID: 4P98Fy40HrzWgT4, Message-ID: <009e1b189d18650cf9841598e2856e97@*.com>, mail_id: bBZk6wDpKvRc, b: 1KA_rIypN, Hits: -, size: 4450146, Subject: "UKEY LICENSEç<9b>¸å<85>³æ<96><87>件 (raw: =?UTF-8?Q?UKEY_LICENSE=E7=9B=B8=E5=85=B3=E6=96=87=E4=BB=B6?=)", From: <*.jia@*.com>, User-Agent: Roundcube_Webmail, helo=localhost, b.key=(?^:^\\.(exe-ms|dll)$), b.com=(?^:^\\.(exe-ms|dll)$), b.rhs=1, b.parts=P=p003,L=1,M=multipart/mixed | P=p002,L=1/2,M=application/zip,T=zip,N=To_*.zip | P=p010,L=1/2/7,T=exe,T=exe-ms,N=IS32U512A.exe, P=p003,L=1,M=multipart/mixed | P=p002,L=1/2,M=application/zip,T=zip,N=To_*.zip | P=p012,L=1/2/9,T=exe,T=exe-ms,N=HexAndStrConverDll.dll, ..., 16622 ms