这是一个特殊的问题。目的是通过 SMTP 为 office365 发送邮件。

我能够始终如一地从我的本地笔记本电脑发送邮件。

但是当部署在我们的服务器上(在防火墙后面)时，它并没有成功。 注意: smtp.office365.com 的端口 587 可访问并已在服务器上确认。以下是它在我的本地计算机上成功运行的属性。

Properties props = new Properties();
props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.connectiontimeout", MAIL_TIMEOUT);
props.put("mail.smtp.timeout", MAIL_TIMEOUT);
props.put("mail.debug", true);
this.session = Session.getInstance(props);
session.setDebug(true);

Transport transport  = session.getTransport();
transport.connect("smtp.office365.com", 587, email, pass);

但在服务器上失败。以下是服务器调试日志:

DEBUG: setDebug: JavaMail version 1.6.2
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]
DEBUG SMTP: useEhlo true, useAuth false
DEBUG SMTP: trying to connect to host "smtp.office365.com", port 587, isSSL false
220 PN1PR0101CA0017.outlook.office365.com Microsoft ESMTP MAIL Service ready at Fri, 28 Jun 2019 06:39:41 +0000
DEBUG SMTP: connected to host "smtp.office365.com", port: 587
EHLO appqa
250-PN1PR0101CA0017.outlook.office365.com Hello [182.73.191.100]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
DEBUG SMTP: Found extension "SIZE", arg "157286400"
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "DSN", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "BINARYMIME", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "SMTPUTF8", arg ""
STARTTLS
220 2.0.0 SMTP server ready
Exception in thread "main" javax.mail.MessagingException: Could not convert socket to TLS;
  nested exception is:
java.net.SocketTimeoutException: Read timed out
at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2155)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:752)
at javax.mail.Service.connect(Service.java:366)
at com.company.app.MailReader.getTransport(MailReader.java:269)
at io.vavr.control.Try.of(Try.java:75)
at com.company.app.MailReader.<init>(MailReader.java:59)
at com.company.services.MailService.getNewMailReader(MailService.java:82)
at com.company.services.MailService.start(MailService.java:46)
at com.company.Main.main(Main.java:34)
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.socketRead(SocketInputStream.java:116)
at java.net.SocketInputStream.read(SocketInputStream.java:171)
at java.net.SocketInputStream.read(SocketInputStream.java:141)
at sun.security.ssl.InputRecord.readFully(InputRecord.java:465)
at sun.security.ssl.InputRecord.readV3Record(InputRecord.java:593)
at sun.security.ssl.InputRecord.read(InputRecord.java:529)
at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:975)
at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1367)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1395)
at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1379)
at com.sun.mail.util.SocketFetcher.configureSSLSocket(SocketFetcher.java:626)
at com.sun.mail.util.SocketFetcher.startTLS(SocketFetcher.java:553)
at com.sun.mail.smtp.SMTPTransport.startTLS(SMTPTransport.java:2150)
... 8 more

最佳答案

检查服务器是否与您的本地计算机具有相同的证书集。

来自服务器的 220 响应并不意味着 TLS session 已经建立，它只是意味着客户端可以开始协商它:

After receiving a 220 response to a STARTTLS command, the client MUST start the TLS negotiation before giving any other SMTP commands. If, after having issued the STARTTLS command, the client finds out that some failure prevents it from actually starting a TLS handshake, then it SHOULD abort the connection. (from RFC 3207)

此时，最有可能出现的问题是缺少证书。

关于java - SMTP 发送邮件不适用于 office365，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/56802175/