Hi Mark. You can always check the logs of the outgoing emails from your Tribe in the admin dashboard. Below is how to do it.

1. You can check the status of the emails from Admin Panel> Members from left-side menu> Invited Users from top-menu> click on Email Activity Log on the top-right, and you should see the status of all the emails send from the community (including notifications and invitations):

2. To better email delivery and to prevent your community emails from ending up in spam, we recommend our customer to install the Sendgrid app9. There are two ways for installing the Sendgrid: Username and Password, or API Key. The API key is safer so we recommend using this method in the app settings.
Now, if the Sendgrid app is enabled, it means that you have created an account on Sendgrid.

3. If you are on Sendgrid Free Plan, your Sendgrid plan does not include the API Key. Therefore, you need to try the Username and Password authentication method to enable the app inside tribe.

If you you are on Sendgrid free plan and you use the API Key as authentication method inside your community, you can see in the Email Activity Log (explained in #1) that the status of the emails are Forbidden:

4. If you are on Sendgrid Paid plan (check the pricing here9), then you can use the API Key as your authentication method inside Tribe. You can either create API... (More)

Unfortunately, we do not support replying through email yet but we do have it in our backlog.

When we implement the feature, we'll do it through an integration with SendGrid and/or MailGun. You'll set your inbound email domain in those 3rd party services and enter the credentials in Tribe App.

Another approach would be just providing a way for our customers to define the reply to address, and let them use Tribe API and any 3rd party service such as SendGrid to receive the email and take the desired action using the API. This will be helpful if you want to create a new post based on each email for instance, but won't work for replying to a post through email. It's worth mentioning implementing a custom reply to address needs way less effort comparing to the first solution.

Let's discuss in comments.

@Timothy Fong26, if you have done the settings for the Sendgrid app on your community, you should not have Tribe branding on your community emails anymore. You will have the branding of the account you have on Sendgrid. 

However, you cannot customize the text for the email notification, and we have no plans to give this option as this is technically not sensible. 

On all Tribe communities, if someone has "liked" your post, you will receive this notification:

<User A liked your questions "how to create community">. 

This text will be generated by Tribe and you cannot replace this text with something else.