邮件服务器使用amavisd-new来签署DKIM，发现发往gmail的邮件DKIM验证失败
Authentication-Results: mx.google.com; spf=pass (google.com: domain of [email protected] designates 61.128.xxx.xxx as permitted sender) [email protected]; dkim=neutral (bad format) [email protected]
安装邮件服务器当时调试是成功验证了的。
于是研究发现 amavisd.conf中dkim_key配置决定接收服务器去查询发送服务器DKIM公钥的变量：
#!! the 2rd param is for DNS TXT recorde like dkim._domainkey
#if use other word eg. issence,then DNS TXT hostname must be issence._domainkey !!!
dkim_key('myhost.com', ' dkim ' , '/var/amavis/myhost-dkim.key');
#if use other word eg. issence,then DNS TXT hostname must be issence._domainkey !!!
dkim_key('myhost.com', ' dkim ' , '/var/amavis/myhost-dkim.key');
如上，粗体的dkim决定你自己服务器域名保存DKIM的TXT记录中的主机名必须是
dkim ._domainkey.myhost.com
我在DNS记录中保存的是dkim ._domainkey.myhost.com但amavisd中却不是dkim这个标志符，不知道什么时候被改成了mail，于是导致接受服务器查询DNS记录失败，并且使用amavisd自带命令验证也失败：
# amavisd testkeys
TESTING#1: mail. _domainkey.myhost.com => invalid (public key: not available)
TESTING#1: mail. _domainkey.myhost.com => invalid (public key: not available)
修改amavisd.conf中相关位置为dkim于是验证成功：
# amavisd testkeys
TESTING#1: dkim._domainkey.myhost.com => pass
TESTING#1: dkim._domainkey.myhost.com => pass
以下是gmail收信后邮件信头：
Authentication-Results: mx.google.com; spf=pass (google.com: domain of [email protected] designates 61.128.xxx.xxx as permitted sender) [email protected]; dkim=pass [email protected]
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=myhost.com; h=
content-transfer-encoding:content-type:content-type:subject
:subject:mime-version:user-agent:from:from:date:date:message-id
:received:received; s=dkim; t=1322140024; x=1323954425; bh=uZ....Hy9hw=; b=Vq/2zo.....ztTOwVc=
content-transfer-encoding:content-type:content-type:subject
:subject:mime-version:user-agent:from:from:date:date:message-id
:received:received; s=dkim; t=1322140024; x=1323954425; bh=uZ....Hy9hw=; b=Vq/2zo.....ztTOwVc=
注：文中以myhost代替实际域名tld部分
注2：文中dkim粗体后面不应该有空格，但编辑器删除这个空格保存后依旧存在。除非把本来应该紧接的字符（比如分号、单引号）也设定成粗体才正常。