I'm trying to create a formula field on the Case object. I would like to store the email addresses in the original email that caused the creation of the Case (Email-to-Case).

When I use the Insert field button in the formula editor, I can navigate to the field I want to use, which is Source.ToAddresses.

Insert Field

However, when I validate the formula, it gives this error:

Error: Specify an object type for the Source field.

I can't find anything on Google that references this error message. Has anyone seen this before or know how I can use that Source.ToAddress in my formula field?

Update: It appears that Source is the name of a lookup field on the Case object to the EmailMessage object. I was originally thinking "Source" was some kind of special cross object special function.

So it looks like my question is specifically related to the Case object and the Source.ToAddress field. I'm still stumped by what the error message means by specify an object type for the source field.

1 Answer 1


In general terms, the 'Source' refers to the channel from where Case was created.

Technically the error is saying there is no Object Type for 'ToAddress'. However, 'ToAddress' is a standard field on 'EmailMessage' object.

In order to use it, you will need to append your formula like this below. Source:EmailMessage.ToAddress

This specifies that the source is an Email and we are using a field value from it to store it on the Case record.

A similar thing goes for cases related to chats, where if you need the status of chats to be stored on the case then you will need to create a formula like this

  • Worked great. Thanks!
    – rodneyaz
    Aug 13, 2019 at 19:36

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