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This page is written for the IT or security administrator of a company receiving TrailerCast email — usually because a vendor your team is evaluating uses TrailerCast to share demo videos, documents, and Decision Rooms. Feel free to forward it to yours.

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What TrailerCast sends

Every message is triggered by a person at the vendor: an invitation to a Decision Room, a shared demo video, a reply to a comment your colleague left, or a reminder about an action item your team agreed to. TrailerCast sends no bulk mail, no marketing, and no automated sequences. Every commercial message carries RFC 8058 one-click unsubscribe headers, honoured immediately.

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Authentication details

SPF, DKIM, and DMARC all pass and align on every message. You can verify against any received message’s Authentication-Results header.

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Allowing TrailerCast in Microsoft 365

Any of the following, in order of preference:
1

Release and mark as not junk (no admin needed)

The recipient opens their quarantine (the “Microsoft 365 quarantine” digest email, or security.microsoft.com/quarantine), selects the TrailerCast message, and clicks Release and Report as not junk. This trains your tenant’s filter directly and is usually enough on its own.
2

Add an allowed domain (admin)

In Microsoft 365 Defender: Email & collaboration → Policies & rules → Threat policies → Anti-spam policies, edit your inbound policy and add trailercast.io to Allowed domains.
3

Mail flow rule scoped to authenticated mail (admin, most precise)

In Exchange admin center, create a mail flow rule: if the sender’s domain is trailercast.io and the message header Authentication-Results contains dmarc=pass, then set the spam confidence level (SCL) to -1. The dmarc=pass condition means a spoofed message can never ride the exemption.

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Allowing TrailerCast in Google Workspace

In the Admin console: Apps → Google Workspace → Gmail → Spam, phishing and malware, add trailercast.io to the approved senders list on your spam policy, or create an inbound gateway/allowlist entry for mail passing DMARC for trailercast.io. TrailerCast links are safe to scan. Defender Safe Links and similar products can fetch and detonate our URLs freely: share links are not single-use, nothing is consumed by an automated visit, and no credential entry is requested at any link destination — a recipient is never asked for a password to view what was shared with them.

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Questions

Email hello@trailercast.io and a human will answer.