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首先在buildConfig中的plugins {
     compile ":mail:1.0.1"
  }
然后再config中配置
grails.mail.default.from = "Xxxx xxxx@gmail.com>"
grails {
	mail {
		host = "smtp.gmail.com"
		username = "xxxx@gmail.com"
		password = "xxxx"
		port=587
		props = ["mail.smtp.auth":"true",
			"mail.smtp.socketFactory.port":"465",
		"mail.smtp.socketFactory.class":"javax.net.ssl.SSLSocketFactory",
			"mail.smtp.socketFactory.fallback":"false"]
	}
}
在resources中加入如下 代码:
beans = {
	taskExecutor(org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor) {
		corePoolSize = 10
		maxPoolSize = 30
		queueCapacity = 6
		keepAliveSeconds = 2000
	}
	mail(SendEmailAsynchronously) {
		taskExecutor = ref('taskExecutor')
	}
}
再建一个 工具类代码如下:

import org.codehaus.groovy.grails.commons.ApplicationHolder
import org.springframework.core.task.TaskExecutor;



class SendEmailAsynchronously {

    static transactional = true
	private static TaskExecutor taskExecutor
	
    def ctx = ApplicationHolder.getApplication().getMainContext();
    def mailService = ctx.getBean("mailService");
    def messageSource = ctx.messageSource
   
	def fromEmail
	def toEmail
	def mailObject
	def emailBody 
	def attach
	public SendEmailAsynchronously() {
	}
    public SendEmailAsynchronously(def toEmail ,def mailObject,def emailBody) {
		this.fromEmail = 'xxx<xxxx@gmail.com>'
		this.toEmail = toEmail
		this.mailObject = mailObject
		this.emailBody = generateContent(emailBody)
       
    }
	
	public SendEmailAsynchronously(def toEmail ,def mailObject,def emailBody,def attach) {
		this.fromEmail = 'xxx xxx@gmail.com'
		this.toEmail = toEmail
		this.mailObject = mailObject
		this.emailBody = generateContent(emailBody)
		this.attach = attach
	   
	}

	public void sendMail() {
		taskExecutor.execute( new Runnable(){
			@Override
			public void run() {
				try {
					println "start send mail"
						mailService.sendMail {
							from fromEmail
							to toEmail
							subject mailObject
							html emailBody
						}
						println "end send mail"
				}catch(Exception e){
				    println e
                    try{
                        User.findByEmail(toEmail).delete()
                    }catch (Exception ue){
                        print "User=="+ue
                    }

				}
			}
		})
	}
	
	
	public void setTaskExecutor(TaskExecutor taskExecutor) {
		this.taskExecutor = taskExecutor
	}
	private String generateContent(bodyContent) {
		if(bodyContent instanceof String) {
			return bodyContent
		}else if(bodyContent instanceof Closure) {
			//bodyContent is a closure
			def sw = new StringWriter()
			def mkp = new groovy.xml.MarkupBuilder(new PrintWriter(sw))
			mkp.html {
				body(bodyContent)
			}
			return sw.toString()
		}
	}

	
	
}