Marketo allows you to set up branded email tracking links, and you can also pay extra to secure them with SSL Certificates. However, even with SSL the URLs still start with http:// and not https:// which could deter users from clicking email links. This idea is for Marketo to begin branded tracking link URLs with https!
Here's a little background info from Marketo's support doc:
Will my tracking links automatically convert to HTTPS?
You will not see tracking links in your Marketo emails changed to HTTPS (they will remain HTTP). However, when an end user clicks the link, if the browser had been instructed to load that domain via HTTPS, the request will be automatically changed to HTTPS and served securely via HTTPS before re-directing to the destination of the link.
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