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Mail server connection failed; nested exception is com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;

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Error trying to send an email in Spring Boot with spring-boot-starter-mail
Hi, Im trying to send an email using Spring boot, but im getting this exception whenever i call the sendSimpleEmail method, none of the parameters are null nor empty:
org.springframework.mail.MailSendException: Mail server connection failed; nested exception is com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;
  nested exception is:
    java.net.ConnectException: Connection refused: connect. Failed messages: com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;
  nested exception is:
    java.net.ConnectException: Connection refused: connect; message exception details (1) are:
Failed message 1:
com.sun.mail.util.MailConnectException: Couldn't connect to host, port: localhost, 25; timeout -1;
  nested exception is:
    java.net.ConnectException: Connection refused: connect
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2210)
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:722)
    at javax.mail.Service.connect(Service.java:342)
    at org.springframework.mail.javamail.JavaMailSenderImpl.connectTransport(JavaMailSenderImpl.java:518)
    at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:437)
    at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:323)
    at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:312)
    at com.JTC.AppPisosAPI.Service.MailService.sendSimpleEmail(MailService.java:27)
    at com.JTC.AppPisosAPI.Controller.EjemploController.getAllUsers(EjemploController.java:31)
    at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
    at java.base/java.lang.reflect.Method.invoke(Method.java:577)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:205)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:150)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:117)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:808)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1071)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:964)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:670)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:779)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:227)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:223)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:217)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:111)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:337)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:115)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:122)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:116)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:126)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:81)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:109)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:149)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilterInternal(BasicAuthenticationFilter.java:166)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:223)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:217)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:223)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:217)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at com.JTC.AppPisosAPI.Config.Security.CustomAuthorizationFilter.doFilterInternal(CustomAuthorizationFilter.java:66)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:103)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:89)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.header.HeaderWriterFilter.doHeadersAfter(HeaderWriterFilter.java:90)
    at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:75)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:112)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:82)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:55)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.session.DisableEncodeUrlFilter.doFilterInternal(DisableEncodeUrlFilter.java:42)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:346)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:221)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:186)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:354)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:267)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:117)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:189)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:162)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:197)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:360)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:399)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:893)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1789)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.base/java.lang.Thread.run(Thread.java:833)
Caused by: java.net.ConnectException: Connection refused: connect
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Net.java:579)
    at java.base/sun.nio.ch.Net.connect(Net.java:568)
    at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:585)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
    at java.base/java.net.Socket.connect(Socket.java:633)
    at java.base/java.net.Socket.connect(Socket.java:583)
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:335)
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:214)
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2160)
This is how my application.properties looks:
spring.mail.username=MyEmail
spring.mail.password=MyPassword
spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.default-encoding=UTF-8
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true
My main class
@SpringBootApplication
public class EmailSendingApp{
   @Autowired static MailService mailService;
   public static void main(String[] args) {
      SpringApplication.run(EmailSendingApp.class, args);
And my method:
public Boolean sendSimpleEmail(String to, String subject, String body){
        SimpleMailMessage msg = new SimpleMailMessage();
        msg.setTo(to);
        msg.setFrom(email);
        msg.setSubject(subject);
        msg.setText(body);
        msg.setSentDate(new Date());
        javaMailSender.send(msg);
    }catch (Exception e){
        e.printStackTrace();
        return false;
    return true;
And this is the bean im using:
@Bean
    public JavaMailSender javaMailSender() {
        JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
        return new JavaMailSenderImpl();
                This could be the issue: Couldn't connect to host, port: localhost, 25; timeout -1; ?? Also which spring boot version, maven, JDK do you use?
– khmarbaise
                Dec 21, 2022 at 10:15
                Is your application.properties in the  in the class path? Looks like the file will be ignored
– Jens
                Dec 21, 2022 at 10:18
                it seems is being ignored but if i create my own variable and use it in another method it picks the value
– Carlosz
                Dec 21, 2022 at 10:28
                Well ... yes.  Or alternatively change the configs so that you don't try to connect to host, port = "localhost", 25 as your email relay.   Basically, the "Connection Refused" response means that no mail service is listening on that address / port.
– Stephen C
                Dec 21, 2022 at 11:00
Try to add below properties too
    spring.mail.properties.mail.smtp.auth=true
    spring.mail.properties.mail.smtp.connectiontimeout=5000
    spring.mail.properties.mail.smtp.timeout=5000
    spring.mail.properties.mail.smtp.writetimeout=5000
    spring.mail.properties.mail.smtp.starttls.enable=true
    spring.mail.properties.mail.smtp.socketFactory.port=465
    spring.mail.properties.mail.smtp.socketFactory.class =javax.net.ssl.SSLSocketFactory
You have to perform following steps to enable mail for your app
Following that, AppPassword needs to be created using the following path:
Login to Gmail
Manage your Google Account
Security
App Passwords
Provide your login password
Select app with a custom name
Click on Generate
For more information you can check : https://www.geeksforgeeks.org/spring-boot-sending-email-via-smtp/
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