I'm trying to send an email from GMail to an Exchange server inside a network secured by an ASA 5510 running version 7.22.
As soon as the email gets send from GMail (webmail) directly everything works fine. But as soon as the user is using the Outlook client to connect to GMail and sends an email, the mail gets dropped on the esmtp inspection rule.
If I remove the esmtp inspection the mail goes through.
Can anyone tell me why the email gets dropped when sent via GMail using Outlook and why the email passes when sent via GMail webmail?
I'm using the default inspection rules.
GMail uses TLS, 'inspect esmtp' drops TLS encrypted email traffic.
You'll need to turn it off and leave it off.