EOF exception during mail due to wrong hostname in EHLO
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Note that this KB was created for the Data Center version of the product. Data Center KBs for non-Data-Center-specific features may also work for Server versions of the product, however they have not been tested. Support for Server* products ended on February 15th 2024. If you are running a Server product, you can visit the Atlassian Server end of support announcement to review your migration options.
*Except Fisheye and Crucible
Summary
Confluence isn't able to send emails and an error message is shown in the user interface (UI) while sending out a test email.
Environment
Confluence server using any SMTP mail server.
Diagnosis
While sending test email, the following error is seen in the UI and the logs.
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An error has occurred with sending the test email:
com.atlassian.mail.MailException: javax.mail.MessagingException: [EOF]
.
Caused by: javax.mail.MessagingException: [EOF]
at com.sun.mail.smtp.SMTPTransport.issueCommand(SMTPTransport.java:2324)
at com.sun.mail.smtp.SMTPTransport.helo(SMTPTransport.java:1678)openssl s_client and other network tools like telnet can connect to the mail server properly.
Upon enabling SMTP debug logs we see the following messages.
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DEBUG: JavaMail version 1.6.2
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
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-relay.mailserver.com", port 587, isSSL false
220 smtp-relay.mailserver.com ESMTP h18sm868180otk.3 - gsmtp
DEBUG SMTP: connected to host "smtp-relay.mailserver.com", port: 587
EHLO localhost
421 4.7.0 Try again later, closing connection. (EHLO) h18sm868180otk.3 - gsmtp
HELO localhost
DEBUG SMTP: EOF: [EOF]ℹ️ SMTP debug logs can be enabled via system property or setting the property mail.debug="true" in the mail session configuration of Confluence.
Cause
Confluence is presenting itself as localhost to the remote mail server.
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EHLO localhostMail server isn't able to identify Confluence and terminates the connection.
Solution
Confluence should be presenting a valid hostname to identify itself. hostname command in Linux is a good way to check what name comes up. Though, if hostname does return the proper hostname, then the following parameter can be configured in the mail session configuration of Confluence.
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mail.smtp.localhost="correct_FQDN.com"Alternatively, we have seen some cases on Linux systems where /etc/hosts contains entries for localhost and the hostname mapping them to 127.0.0.1. On that case, make sure the hostname entry comes first:
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127.0.0.1 localhost
127.0.0.1 <hostname>Change it to:
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