SRS (Sender Rewriting Scheme) is a technique used by mail forwarding agents like ImprovMX to ensure SPF policies are adhered to. Ultimately it results in fewer emails being flagged as spam by destination inboxes such as Gmail, Outlook, or Yahoo.

ImprovMX currently implements a custom version of SRS to properly pass SPF policies. But this custom SRS might be hurting deliverability because it doesn't look exactly like what others are implementing.

ImprovMX takes email deliverability very seriously, so we will implement SRS.