$ mailx
s-nail version v14.8.6.  Type ? for help.
"/var/mail/christoph": 3 messages
>O  1 mdadm monitoring   Sun Mar 19 13:50   31/950   Fail event on /dev/md0:christoph-pi
 O  2 mdadm monitoring   Mon Mar 20 07:36   29/905   DegradedArray event on /dev/md0:christoph-pi
 O  3 mdadm monitoring   Tue Mar 21 07:36   29/905   DegradedArray event on /dev/md0:christoph-pi
? 1
[-- Message  1 -- 31 lines, 950 bytes --]:
From root@christoph-pi.home  Sun Mar 19 13:50:06 2017
From: mdadm monitoring <root@christoph-pi.home>
To: root@christoph-pi.home
Subject: Fail event on /dev/md0:christoph-pi
Message-Id: <20170319125006.9BD4D40BCA@christoph-pi.home>
Date: Sun, 19 Mar 2017 13:50:06 +0100 (CET)

This is an automatically generated mail message from mdadm
running on christoph-pi

A Fail event had been detected on md device /dev/md0.

It could be related to component device /dev/sda1.

Faithfully yours, etc.

P.S. The /proc/mdstat file currently contains the following:

Personalities : [raid1]
md0 : active raid1 sdb1[1](W) sda1[0](F)
      124967936 blocks super 1.2 [2/1] [_U]
      bitmap: 0/1 pages [0KB], 65536KB chunk

unused devices: <none>

? 2
[-- Message  2 -- 29 lines, 905 bytes --]:
From root@christoph-pi.home  Mon Mar 20 07:36:06 2017
From: mdadm monitoring <root@christoph-pi.home>
To: root@christoph-pi.home
Subject: DegradedArray event on /dev/md0:christoph-pi
Message-Id: <20170320063605.CD0BC40BCA@christoph-pi.home>
Date: Mon, 20 Mar 2017 07:36:05 +0100 (CET)

This is an automatically generated mail message from mdadm
running on christoph-pi

A DegradedArray event had been detected on md device /dev/md0.

Faithfully yours, etc.

P.S. The /proc/mdstat file currently contains the following:

Personalities : [raid1]
md0 : active raid1 sdb1[1](W)
      124967936 blocks super 1.2 [2/1] [_U]
      bitmap: 1/1 pages [4KB], 65536KB chunk

unused devices: <none>

? 3
[-- Message  3 -- 29 lines, 905 bytes --]:
From root@christoph-pi.home  Tue Mar 21 07:36:06 2017
From: mdadm monitoring <root@christoph-pi.home>
To: root@christoph-pi.home
Subject: DegradedArray event on /dev/md0:christoph-pi
Message-Id: <20170321063606.82883437C5@christoph-pi.home>
Date: Tue, 21 Mar 2017 07:36:06 +0100 (CET)

This is an automatically generated mail message from mdadm
running on christoph-pi

A DegradedArray event had been detected on md device /dev/md0.

Faithfully yours, etc.

P.S. The /proc/mdstat file currently contains the following:

Personalities : [raid1]
md0 : active raid1 sdb1[1](W)
      124967936 blocks super 1.2 [2/1] [_U]
      bitmap: 1/1 pages [4KB], 65536KB chunk

unused devices: <none>

?