Set site to send via whitelabel domain?

[tevyaw]

As far as I can tell, it only sends via the main/default whitelabel domain. I'd like to be able to select the whitelabel domain that any given site sends through.

I posted about this on WP.org support forums as well: https://wordpress.org/support/topic/way-to-choose-which-whitelabel-domain-to-send-from/ but there doesn't seem to be any support from SendGrid there.

Please add the ability to determine which whitelabel domain a site should send through. Thanks!