启动sendmail竟然需要很长时间，网上查了查，有很多人碰到类似问题，但是一般都是关掉sendmail服务或者关掉dns了事，咱们现在要用它，自然不能关掉了事，dns也不能关，关了服务器没法解析域名
毫无疑问，sendmail去做dns lookup，并且无法lookup到域名，在等待解析超时！
这里我的主机名叫mymachinename，里面也指定了nameserver，应该能正常做dns解析了，既然他无法解析域名，自然这是个本地域名，难道是hosts里面的问题，查看了一下hosts文件：
# Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost 192.168.1.28 mymachinename
好像也没发现啥不对的，他在解析啥呢，看看log去，找到/var/log/maillog（也可能在messages），看到如下内容：
Dec 11 14:25:01 mymachinename sendmail[22710]: starting daemon (8.13.8): SMTP+queueing@01:00:00 Dec 11 14:25:01 mymachinename sm-msp-queue[22717]: My unqualified host name (mymachinename) unknown; sleeping for retry Dec 11 14:28:08 mymachinename sendmail[22803]: My unqualified host name (mymachinename) unknown; sleeping for retry Dec 11 14:35:23 mymachinename sendmail[22944]: My unqualified host name (mymachinename) unknown; sleeping for retry Dec 11 14:35:57 mymachinename sendmail[22962]: My unqualified host name (mymachinename) unknown; sleeping for retry Dec 11 14:36:54 mymachinename sendmail[22979]: My unqualified host name (mymachinename) unknown; sleeping for retry
竟然是无法解析mymachinename，有点意思，直接去ping mymachinename自然是没问题，突然想到好像FQDN里面规定域名必须用”.”结尾，难道是hosts里面少了一个”.”，尝试修改hosts文件：
# Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost.localdomain localhost 192.168.1.28 mymachinename. mymachinename
启动sendmail，刷一下就启动了。
回头想想，问题其实很简单，但是在网上却没找到什么好的方案，说明都挺懒的，能绕都绕过去了。
