SSL Connect Error on SMTPS Settings

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SSL Connect Error on SMTPS Settings

L2 Linker

We have problem with SMTPS configuration on Palo alto Firewall

so we have the SMTPS Certificate and already inject to the firewall

Our users says that the certificate is the certificate CA and when we test the email connection, the firewall shows error 'SSL Connect Error', we try on port 465 and using TLS 1.2


We have another brand network device, and the tac support on that brand said their device require the parameter 'extended key usage server authentication' in the certificate to setup the SMTPS.


Are in the palo alto firewall need this too in the certificate so we can config the SMTPS?

or is there any docs about how to troubleshoot the certificate like this?

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Community Team Member

Hi @DennyChanditya ,


What type of email server do you use? 

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i not familiar with the smtp/email servers type, how to identified that server type?


i only get the certificate file from our customer, they said it was the email server certificate CA. 

i still search about certificate requirement for setup the SMTP over TLS.

Cyber Elite
Cyber Elite


Have you tried either of the following:

Try sending without TLS

Use port 25




We've request open tac to troubleshoot this case, since our users not recommend to use smtp on port 25, so we should use the smtps instead. if the tac says it cannot use smtps so we go through with smtp.

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