Gmail Not Sending (SMTP) Through Mac Mail App

[BillyBragg]

Greetings,

My organization uses Gmail through the Mac Mail app. Incoming emails are working, but outgoing/sending is not. Below is a log of my co-worker trying to send a message. I am kind of a noob and hoping for someone who can help translate.

OR maybe I am not even looking at the right log? 

Thanks!

[AEK]

Hi Billy

Can you post a screenshot of the "block-high-risk" application profile?

On that profile you may also try allow SMTPS app under "Application and Filter Overrides" and see if it fixed the issue.

[BillyBragg]

Hi AEK,

Thank you for your reply. I did add SMTPS under the "Application and Filter Overrides" earlier today but I still had the same issue.

[AEK]

Hello Billy

On the log screenshot I see action "server reset", which means the remote mail server closed the TCP connection.

We need some more investigation, can you please run the below command from the same host and share the output?

telnet 142.250.123.109:587

[BillyBragg]

Before I do that, I wanted to update that we turned off SMTPS in SSL/SSH Inspection > Protocol Port Mapping and that fixed the issue for at least one test user. However, in order to turn off SMTPS you have to turn off "Inspect All Ports" which we're not sure what doing that opens us up to.

[BillyBragg]

Does turning off "Inspect All Ports" literally turn off inspecting ALL ports or is it just for the ports listed below it in the GUI?

[AEK]

Good finding. You may troubleshoot by turning it on again, turn on "Log SSL anomalies" in the SSL profile, redo the test, then see the SSL logs if there is some error.

By the way are you using deep inspection?

[BillyBragg]

Yes sir, we are using deep inspection.

Also wanted to follow up on my other question, does turning off "Inspect All Ports" literally turn off inspecting ALL ports or is it just for the ports listed below it in the GUI?

Thank you!!

[AEK]

As per my knowledge, "Inspect All Ports" will inspect ALL ports (from 1 to 0xFFFF). I think it is good practice to enable it since some apps may use other ports for SSL traffic.

[BillyBragg]

The problem is that I can't seem to turn off the inspect SMTPS slider without first turning off the Inspect All Ports" slider. :\