AWSでのメール送信でタイムアウトが頻繁に発生 - 親バカエンジニアのナレッジ帳

SpringBoot + EC2の構成で、メール送信エラーが頻発
さくらサーバのサポートセンターに問い合わせ
本当の原因はEC2の送信制限
ちなみに…

SpringBoot + EC2の構成で、メール送信エラーが頻発

SpringBoot + EC2のアプリケーションでメルマガ機能を作成していましたが、どうにもメール送信が途中で止まってしまうということで、ログを確認すると以下のようなエラーログが頻発していました。
要はタイムアウトが発生しているようです。

2019-02-13 16:47:51.263 ERROR 27325 --- [pool-4-thread-1] o.s.s.s.TaskUtils$LoggingErrorHandler    : Unexpected error occurred in scheduled task.

org.springframework.mail.MailSendException: Mail server connection failed; nested exception is com.sun.mail.util.MailConnectException: Couldn't connect to host, port: wwwxxxx.sakura.ne.jp, 25; timeout 5000;
  nested exception is:
java.net.SocketTimeoutException: connect timed out. Failed messages: com.sun.mail.util.MailConnectException: Couldn't connect to host, port: wwwxxxx.sakura.ne.jp, 25; timeout 5000;
  nested exception is:
java.net.SocketTimeoutException: connect timed out
    at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:432) ~[spring-context-support-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:345) ~[spring-context-support-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mail.javamail.JavaMailSenderImpl.send(JavaMailSenderImpl.java:340) ~[spring-context-support-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at com.thegate12.batch.SendMailBatch.lambda$execute$0(SendMailBatch.java:77) ~[classes/:1.0-SNAPSHOT]
    at java.util.ArrayList.forEach(ArrayList.java:1255) ~[na:1.8.0_151]
    at com.thegate12.batch.SendMailBatch.execute(SendMailBatch.java:47) ~[classes/:1.0-SNAPSHOT]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]
    at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]
    at org.springframework.scheduling.support.ScheduledMethodRunnable.run(ScheduledMethodRunnable.java:65) ~[spring-context-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.scheduling.support.DelegatingErrorHandlingRunnable.run(DelegatingErrorHandlingRunnable.java:54) ~[spring-context-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_151]
    at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:308) [na:1.8.0_151]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:180) [na:1.8.0_151]
    at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:294) [na:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149) [na:1.8.0_151]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624) [na:1.8.0_151]
    at java.lang.Thread.run(Thread.java:748) [na:1.8.0_151]
Caused by: com.sun.mail.util.MailConnectException: Couldn't connect to host, port: wwwxxxx.sakura.ne.jp, 25; timeout 5000
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2118) ~[javax.mail-1.5.6.jar:1.5.6]
    at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:712) ~[javax.mail-1.5.6.jar:1.5.6]
    at javax.mail.Service.connect(Service.java:366) ~[javax.mail-1.5.6.jar:1.5.6]
    at org.springframework.mail.javamail.JavaMailSenderImpl.connectTransport(JavaMailSenderImpl.java:501) ~[spring-context-support-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    at org.springframework.mail.javamail.JavaMailSenderImpl.doSend(JavaMailSenderImpl.java:421) ~[spring-context-support-4.3.5.RELEASE.jar:4.3.5.RELEASE]
    ... 18 common frames omitted
Caused by: java.net.SocketTimeoutException: connect timed out
    at java.net.PlainSocketImpl.socketConnect(Native Method) ~[na:1.8.0_151]
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) ~[na:1.8.0_151]
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) ~[na:1.8.0_151]
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) ~[na:1.8.0_151]
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) ~[na:1.8.0_151]
    at java.net.Socket.connect(Socket.java:589) ~[na:1.8.0_151]
    at com.sun.mail.util.WriteTimeoutSocket.connect(WriteTimeoutSocket.java:113) ~[javax.mail-1.5.6.jar:1.5.6]
    at com.sun.mail.util.SocketFetcher.createSocket(SocketFetcher.java:329) ~[javax.mail-1.5.6.jar:1.5.6]
    at com.sun.mail.util.SocketFetcher.getSocket(SocketFetcher.java:238) ~[javax.mail-1.5.6.jar:1.5.6]
    at com.sun.mail.smtp.SMTPTransport.openServer(SMTPTransport.java:2084) ~[javax.mail-1.5.6.jar:1.5.6]
    ... 22 common frames omitted