I have two different domains with GoDaddy.com.
1. Domain1 exists only on GoDaddy with their MX record, nothing has been changed on this account in years.
2. Domain2's DNS Zone file is with GoDaddy and had their MX record until recently. I have modified the MX record to point to my in-house Exchange server. My Exchange server receives the incoming email and looks for a box. If no box exists it sends it to GoDaddy to find a box there.
Up until 3/6 all emails for both domains were working fine. On 3/9 I found out a few emails that were sent to Domain1.com were rejected due to SPF Record Unauthorized. Same company that has been sending me emails without issue and all of a sudden cannot send me emails.
Around the same time I started moving Domain2.com over to Exchange and changing the MX record to point to me directly.
On that domain I have multiple complaints from companies indiicating their emails are bouncing with the same error. However; I do not believe they are bouncing if a box exists on the Exchange server (I will have to double check that).
Therefore, my questions are:
1. Why the sudden rejection, especially on a domain that hasn't changed?
2. Are the email headers for incoming email being modified when it passes through my Exchange server (for Domain2) and therefore being rejected by GoDaddy when my Exchange server passes it onto GoDaddy?
If you think number 2 is true then why does it only reject a few?
Thank you for your time and help.