首先上官方链接：

https://docs.microsoft.com/zh-cn/sharepoint/administration/outgoing-email-configuration?tabs=CA2019farm%2C2019farm%2CCASEweb%2C2019web

原因是 组的话默认不能发送匿名邮件

方法1 .给需要发送的组修改属性，但这个方式不是很推荐，因为组一旦很多而且会有安全风险

Get-DistributionGroup "Group Name"|Select-Object  RequireSenderAuthenticationEnabled

Get-DistributionGroup "Group Name" | Set-DistributionGroup -RequireSenderAuthenticationEnabled:$false

方法2. 通过创建stmp服务来满足 匿名发送

这个方式原理就是 利用邮件中继的思路，如果是非exchange邮件系统的第三方邮件系统建议这么处理

方法3 比较推荐

这个地方其实页面上配置 会发现还是发不出去，他这个是利用windows身份认证的机制，在Sharepoint的 powershell里执行命令即可

$CentralAdmin = Get-SPWebApplication -IncludeCentralAdministration | ? { $_.IsAdministrationWebApplication -eq $true }

$SmtpServer = "mail.example.com"
$SmtpServerPort = 587
$FromAddress = "user@example.com"
$ReplyToAddress = "replyto@example.com"
$Credentials = Get-Credential    //此处会弹出一个框，输入邮箱UPN名或 domain\ad 密码即可

Set-SPWebApplication -Identity $CentralAdmin -SMTPServer $SmtpServer -SMTPServerPort $SmtpServerPort -OutgoingEmailAddress $FromAddress -ReplyToEmailAddress $ReplyToAddress -SMTPCredentials $Credentials

SharePoint证书校验问题

A certificate validation operation took 30031.6826 milliseconds and has exceeded the execution time threshold.  If this continues to occur, it may represent a configuration issue.  Please see http://go.microsoft.com/fwlink/?LinkId=246987 for more details.

对应方法：https://docs.microsoft.com/en-US/sharepoint/troubleshoot/sites/site-slowness-because-of-sts-certificate-crl-checking