# Implement OWA Assisted Mail Submission in a different mail server or secure email gateway

Most organizations use Exchange Online as their email gateway. However, if you are using a Secure Email Gateway (SEG), such as ProofPoint or Mimecast, and require outbound Zivver messages to pass through your SEG, consider the following.

## Requirements

- The SEG must be able to [connect to the Zivver smart host](https://docs.zivver.com/en/admin/smtp/connect-to-zivver-smtp-gateway.html).
- The SEG must be able to [filter outbound email on a custom email header](https://docs.zivver.com/en/admin/owa/owa-ams/filter-outbound-zivver-messages-on-a-custom-mail-header.html).
- All emails with the `zivver-relay` header should be routed to `smtp.zivver.com`, including internal recipients.
- The SEG should not affect or trim any email headers starting with `x-zivver`.
- The **Zivver-message-info** attachment should not be altered.

Updated on 2026-06-18