SMTP Settings Troubleshooting

While you might encounter the failure issue during testing and normal operations (send/receive the Email failed) with the Email account.

Before the troubleshooting, you would need to log in the SSH for executing commands. Refer here

Step 1. Ensure the device could access the Internet

Try to use ping & nslookup command to test smtp domain.

If failed, please check whether the DNS address is available or not.

Step 2. Check the SMTP/POP3 Servers’ Settings

Enable the default protocol 

  • The SMTP Server’s port is 25 by default.
  • The POP3 Server’s port is 110 by default.

Enable the TLS protocol (For the Gmail or the Exchange Server)

  • The SMTP Server’s TLS port is 587.
  • The POP3 Server’s TLS port is 995.


For Gmail or Exchange server, you need to enable the TLS protocol.


Step 3. Enable the SMTP/POP/IMAP options of Email Servers

Gmail Server Settings

Step 4. Debugging the ssmtp procedure and check the typical reply error codes

S-Series PBX

Enter the SSH global interface, enter this path /ysdisk/support/tmp and create one xxx.eml file, like testsysmailbox.eml. Input the testing contents into the testsysmailbox.emil file, refer here:

cd /ysdisk/support/tmp/

vi testsysmailbox.eml 

From: IPPBX <>

To: Test <>

Subject: Test mail for IPPBX

MIME-Version: 1.0

Press ESC and input command :wq to save the current contents. 

From: the administrator’s Email address of PBX

To: the destination’s Email address, would be the administrator’s by default. (User can change the destination email address in the line of “TO” filed)

And then, running the ssmtp debug command to see the debug details.

ssmtp -D /ysdisk/etc/mailbox/sysmail -vt </ysdisk/support/tmp/testsysmailbox.eml 


For TGv3 Gateway

Enter this path /ysdisk/support/tmp, go to create one xxx.emil file, like mail.eml. Input the testing contents into the mail.eml file, refer here:

touch /ysdisk/support/tmp/mail.eml

vi mail.eml

From: TG400 <>

To: shay <>                           

Subject: Test SMTP for TGV3

MIME-Version: 1.0


Press ESC and input command :wq to save the current contents. 

And then, running the ssmtp debug command to see the debug details.

ssmtpsms -vt < /ysdisk/support/tmp/mail.eml



For U-Series, TGv2 and other gateways

Refer this guide: SMTP Debug For MyPBX & Gateways


The Typical Errors

  • Locked Port

This may be caused by the router/firewall security policies has enabled the restriction to SMTP port 25.

  • Wrong Password (535 Error)

This error means this Email Server’s password should be the Authentication code.

  • Wrong Password (535 Error)

This error means Password Authentication is failed, check if the password is correct or includes the special characters or not.

  • Locked account (534 Error)

Send-mail: Authorization failed 534 5.7.14, this problem may be caused by the Gmail account has been locked out due to many 3rd party less secure apps tried to log in this mail account, use this link Unlock Gmail Account and click CONTINUE to unlock this account.


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  • 0

    @step 3; testsystemailbox.eml must be testsysmailbox.eml (as in the screenshot)

  • 0

    Hello Johan, thank you for correcting the information, whole the article has corrected and optimized.

    Thanks for your supporting. 

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