Exchange server Check connection Email port 25

Question

Our Exchange system, I'm having trouble

• The application connects to the email system to send error messages

(ManageableThread.java:914) ERROR SendEmailNoAttachFile:914 - session
javax.mail.AuthenticationFailedException: 535 5.7.3 Authentication unsuccessful
at com.sun.mail.smtp.SMTPTransport$Authenticator.authenticate(SMTPTransport.java:826)
at com.sun.mail.smtp.SMTPTransport.authenticate(SMTPTransport.java:761)
at com.sun.mail.smtp.SMTPTransport.protocolConnect(SMTPTransport.java:685)
at javax.mail.Service.connect(Service.java:317)
at telsoft.thread.report.SendEmailNoAttachFile.sendMessage(SendEmailNoAttachFile.java:108)
at telsoft.thread.report.SendEmailNoAttachFile.processSession(SendEmailNoAttachFile.java:73)
at com.telsoft.thread.ManageableThread.session(ManageableThread.java:911)
at com.telsoft.thread.ManageableThread.run(ManageableThread.java:852)
at java.lang.Thread.run(Thread.java:748)
-> You have to tell the application side to turn off TLS before sending it again

Pop3 users send using port 25, it reports an authentication error, but it works again with port 587

Answer 1

Hi @LcChnh-7604

I would like to confirm with you first:
Are you using Exchange Online (Office 365) or are you using Exchange On-premises as email service?

From the log it seems the application is connecting to port 25 on Exchange to send emails.
To me it should be the expected behavior.
Since port 25 doesn't require authentication (otherwise the server would be unable to receive anonymous emails), you may need to use port 587 instead to authenticate and send emails.

Here is also a link about how to configure POP3 and SMTP settings (applied to Exchange Online) : POP, IMAP, and SMTP settings

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