DKIM (DomainKeys Identified Mail)
"DKIM allows an organization to take responsibility for transmitting a message, in a way that can be verified by a recipient. The organization can be the author's, the originating sending site, an intermediary, or one of their agents."
Source: www.dkim.org
SPF (Sender Policy Framework)
"The Sender Policy Framework (SPF) is an open standard specifying a technical method to prevent sender address forgery."
Source: www.openspf.org
What does that mean?
Basically, DKIM and SPF are ways for Gmail, Hotmail, and other email providers to make sure their users know exactly where their emails come from. Since you can virtually use any email address in the From: field, email providers want to prevent scams from people pretending to be a bank by inserting a fake bank email address into the From: field. Email providers will therefore add a "Via" or "On Behalf of" tag when the From: field doesn't match the domain it came from. It looks like this:
Since Critsend is a third party in your email's transmission, your emails will appear to be from Critsend servers and not your own. However, this can be removed by whitelisting your domain using DKIM or SPF.
