Choose the best email security for Google Workspace by counting what still reaches inboxes after Gmail's own filters, which Google says block 99.9% of spam and phishing attempts, along with malware¹. Then check the access each add-on requests. AegisAI is one example of an add-on, and it reads mail through the Google Workspace API after delivery²⁰.

What you can do by the end

When is native Google Workspace email protection not enough?

It is not enough when confirmed threats still arrive in inboxes after Gmail has filtered them. Count those in a trial before you buy. Gmail's advanced phishing and malware protection has three groups of settings: attachments; links and external images; spoofing and authentication⁴. Gmail's default is to show warnings and move untrustworthy email to spam. Each setting also offers a Quarantine action, which holds messages for admin review and hides them from users.

Attachment scanning has a cost in time. Security Sandbox scanning can delay message delivery by up to 3 minutes⁵. Not every edition includes it, so check yours against Google's list.

Business email compromise is the second largest loss type in the FBI's 2025 report, with $3,046,598,558 in reported losses¹⁹. The page on which Google Workspace settings and logs stop business email compromise lists the native controls in order.

Question to ask a vendor: which confirmed threats did your trial find in mail that Gmail had already delivered to the inbox?

Which is the right architecture: API-native or a secure email gateway?

Pick the architecture by what you are willing to change in mail routing. A secure email gateway needs the MX records for your domain pointed at the gateway¹⁶. Every inbound message then passes through it before Gmail sees it. An API-native add-on connects to the tenant and reads mail that Gmail has already delivered, so routing stays as it is.

The gateway route changes authentication too. Gmail does not enforce the sender's DMARC policy for messages that arrive from the inbound gateway¹⁷. Plan for that before the MX change. The page on how to add a third-party email security layer to Google Workspace walks through both set ups.

Question to ask a vendor: does deployment touch our MX records, and what are the exact rollback steps?

Check what the add-on is allowed to read and change

An API add-on can read and change only what its OAuth scopes and your app access settings allow, so read both before you approve it. The gmail.readonly scope lets an app view messages and settings, and Google classifies it as restricted¹⁴. The gmail.modify scope cannot permanently delete mail past the trash; the full mail.google.com scope can.

In the Admin console, set each app to Trusted, Limited, Specific Google data or Blocked¹⁰. For Gmail, you can also restrict access to high-risk scopes. Domain-wide delegation gives the app access to the data of all your users¹². Deleting that client stops every app that depends on it at once.

Question to ask a vendor: which Gmail API scopes do you request, which of them can move or delete mail, and do you need domain-wide delegation?

Ask what happens to mail when the add-on is offline

Mail should keep arriving when the add-on is down. An API add-on reads mail after Gmail delivers it, so an outage on its side pauses detection and leaves delivery alone. A gateway sits in the MX path, so inbound mail depends on the gateway being up. The post on what happens to mail flow if an email security vendor goes down covers both cases.

Question to ask a vendor: if your service is unavailable for an hour, where is our inbound mail, and what do you scan when you come back?

Check how removal works after delivery

Removal should reach every copy of a message including forwards. It should also leave a record. Google's security investigation tool lets admins use Gmail log data to find and erase malicious emails⁹. Email Log Search covers up to 30 days in a custom search; older messages need the recipient's full address and the message ID⁷. It does not show message contents.

Ask whether the add-on deletes mail or moves it to trash. That choice follows from the scope it holds.

Question to ask a vendor: when you remove a message, which mailboxes does it leave, where does it go, and where is the record of the action?

Ask for a reason with every verdict

Ask for a plain-language reason with every block and every removal. The reason should name what the message asked the reader to do and the signal that decided the call. Read the reasons for one week of trial verdicts before you turn on removal. The guide on how to evaluate API based email security lists the logging and SIEM checks to run alongside.

Question to ask a vendor: which reason and signals decided the call on one removed message and one allowed message from our trial?

Which key evaluation criteria does each approach to Google Workspace email security meet?

Test top email security solutions for Google Workspace with this checklist

Answer these 10 questions yes or no, with evidence from a trial on your own tenant.

How AegisAI handles this

AegisAI sits out of band and reads mail through the Google Workspace API after delivery, with no MX change and no gateway. It connects with an OAuth grant your admin controls and can revoke²³. It runs in monitoring mode first, and removal needs write access your admin grants and can revoke²¹. With enforcement on, it removes confirmed threats from every mailbox they reached and logs each action with its reasoning²⁵. Mail keeps flowing during an outage, while detection pauses until the service returns²².

Which compliance considerations apply for HIPAA and SOC 2?

Two apply first: the agreement with Google and the evidence trail of the add-on. Customers subject to HIPAA must enter a Business Associate Amendment with Google before they use covered services with protected health information¹⁸. An add-on that reads mail handles that information as well, so ask for its own agreement and its SOC 2 report.

Email Log Search keeps a 30 day window for custom searches. Ask how long the add-on keeps its verdict and removal logs, and whether your auditors can read the export. For teams that also run Microsoft 365, the page on running email security across Google Workspace and Microsoft 365 covers keeping compliance and DLP consistent on both.

Question to ask a vendor: will you sign a business associate agreement, can we see your SOC 2 report, and how long do you keep verdict logs?

How to measure it in 30 days

Track three numbers from the first day of the trial.

Questions people ask

Sources