How is the "From" field populated in the Case Feed Email (Answer Customer) Publisher?

Question

We are using Case Feed and Email To Case. I am trying to figure out what the default value of 'From' is, it seems to be different from Case to Case.

Answer 1

From Our support teams need to send from different email addresses: (my emphasis)

The case feed setting "Specify From Address(es)" allows a default address to be specified for the case feed. If the department Users are assigned Case records types and page layouts, then each department may have a different From address.

For example:

The Users for department A will have;
Case Record Type: Team A
Page Layout: Team A
Team A Case Feed Layout from Address: [email protected]

The Users for department B will have;
Case Record Type: Team B
Page Layout: Team B
Team B Case Feed Layout from Address: [email protected]

That could certainly explain why users from different departments are getting different default from addresses.

There is also Email to Case: Default FROM Address when Replying to an Inbound Email Message:

Description
When Replying to an Inbound Email Message on a Case record, what is the default value that populates in the FROM drop down menu field?

Resolution
A Salesforce user can specify the sending address of the email in the From drop-down list for email addresses associated with Email-to-Case and Organization Wide Addresses, in addition to the logged in user's email address.

When creating a new outbound Email-to-Case message, the From address is auto-populated with the logged in user's email address. When replying to an inbound message, the From address is auto-populated with the routing address to which the email was sent.

If users need to use a specific FROM email address (such as an email-to-case address [email protected]), they will have to manually select it from the FROM dropdown list as there currently is no setting to specify a default reply-to/FROM email address for all outbound communications.