从Spring Boot拒绝连接到主机：smtp.gmail.com端口：587

Question

I am trying to send email using spring-boot-starter-mail and the result is

Failed message 1: com.sun.mail.util.MailConnectException: Couldn't connect to host, port: smtp.gmail.com, 587; timeout 5000;

My application.properties are

spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=<email>
spring.mail.password=<password>

# Other properties
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


# TLS , port 587
spring.mail.properties.mail.smtp.ssl.trust=smtp.gmail.com
spring.mail.properties.mail.smtp.starttls.required=true
spring.mail.properties.mail.smtp.starttls.enable=true

I have tried myriad combinations and all roads lead to this same exception! I can telnet to smtp.gmail.com 587 and receive a response

220 smtp.gmail.com ESMTP e82sm2105370oia.36 - gsmtp

Many links I followed suggested a firewall might be to blame. Has anyone seen this issue?

Answer 1

Are you using a proxy? If your telnet is successful then it's using some configuration that your spring application lacks, perhaps an environment variable such as HTTP_PROXY is set? The most likely scenario I come across in this situation is this issue. You would them need to set this as normal for any java application by passing the

-Dhttp.proxyHost=127.0.0.1 -Dhttp.proxyPort=3128

arguments.