I need some help understanding the nature of this service with relation to incoming emails.
We have adopted SendGrid for ensuring deliverability of our application's emails (automated stuff like confirmation messages, etc.) I've followed their whitelabel wizard to setup our dns.
Since it now seems that all incoming mail to our domain is being routed through sendgrid, I am at a loss for how to ensure our non-virtual users (think secretary at her desk) are going to configure their mail clients to receive their emails as normal, since everything is on the same domain. SendGrid tech support doesn't seem to understand my question.
I setup the dns in BIND to follow their specs - created the subdomain
email. they assigned and installed the SPF records etc. SendGrid tech support has advised me to make all the mail clients login to this subdomain (which is CNAMEd to their dns) and use our account login from SendGrid... but how the heck would this identify the user retrieving mail? Thunderbird would just login with our account creds, so nothing specific about the reciepient would be transmitted... I think they are assuming I want to pick up all the application emails, but what I really want to get setup right now is just proper routing behavior.
Am I misunderstanding the process here? Is there really no way we can operatate normal incoming delivery on the same domain that is hooked into sendgrid for outgoing (both for app emails and regular, non-virtual compositions)?
Any guidance at all would be appreciated... whenever I have to wear the sysadmin hat it really mystifies me.