Cisco Pix blocks SMTP traffic with it’s ESMTP Inspection feature!Comments (1)
Cisco Pix has by default enabled a feature called ESMTP inspection in its software. It will drop all packages if using Transport Layer Security (TLS) encryption for email communication.
In order to allow the e-mails with TLS enabled, disable the ESMTP inspection feature as this output shows:
pix(config)#policy-map global_policy pix(config-pmap)#class inspection_default pix(config-pmap-c)#no inspect esmtp pix(config-pmap-c)#exit pix(config-pmap)#exit