Any overhead with TLS?

[GRAHAM CAREY]

One of our customers wants us to setup TLS with them. They will be the only customer that will be setup to use TLS. I am wondering if there is any overhead or delay caused by settign up TLS on the Ironport.

ie. For all the other incoming connections that don't use TLS, does it cause a few seconds lag while it checks for TLS, then falls back to standard SMTP?

[rakeshshankarappa]

If you're planning to implement TLS for this specific client, then other clients will not get impacted.

Also, you would not notice even a second's delay with TLS communication enabled emails.

[Andreas Mueller]

Hello Graham,

there is usually no delay to be significant for message processing when sent/received via TLS. What however is important to know is that compared to normal SMTP connection, a TLS connection takes at least ten times more resources. That is important to know in if the customer plans to use TLS extensively.

Hope that helps,

Andreas