An inbound email gateway sits in front of your mail platform at the MX level and filters mail before your provider sees it. It adds a layer; it doesn't replace what your provider does. Each comparison below states where the built-in option is stronger, where a gateway helps, and the setup risks of running both.
Built-in protection vs a gateway
Microsoft 365 built-in filtering vs a gateway
Exchange Online Protection comes with every Microsoft 365 tenant. When a gateway in front of it helps, what it costs, and how to avoid weakening Microsoft's own checks. Setup steps are on the Microsoft 365 platform page.
Microsoft Defender for Office 365 vs a gateway
What Defender Plan 1 and Plan 2 add, where Defender is stronger than any MX gateway, and how to run both without double link rewriting.
Google Workspace built-in protection vs a gateway
Gmail's spam, phishing and malware filtering and its advanced settings, the gaps some organizations notice, and how the inbound gateway setting works. Setup steps are on the Google Workspace platform page.
Pricing models
SpamTitan alternative
Per-user pricing with a 25-user minimum versus a flat price per domain, side by side with published prices.
Mimecast alternative
A broad security suite with custom pricing, compared with a focused, per-domain filter for smaller teams.
Proofpoint Essentials alternative
What the move to 365 Total Protection means for Essentials customers, and when a simpler filter fits.
Barracuda Email Protection alternative
Bundled plans with sandboxing and continuity, compared with per-domain filtering and quarantine digests.
N-able Mail Assure alternative
An MSP-focused service with long spooling and archiving, compared with transparent per-domain pricing.
MX Guarddog alternative
A low-cost per-address filter that is cheaper than us for small offices, compared with flat per-domain pricing and what it includes.
Hornetsecurity 365 Total Protection alternative
A four-plan Microsoft 365 security suite on a quote, compared with a focused inbound filter at published prices.
Mailprotector alternative
An email security stack sold through MSPs, with published support hours, compared with filtering you can buy directly.
MailChannels Inbound alternative
Per-domain filtering offered through web hosts, compared with per-domain filtering you buy yourself.
SpamExperts alternative
N-able's filtering platform for web hosts and ISPs, and how it relates to Mail Assure, compared with a filter that stays with you when you change host.
Per-domain vs per-user pricing
Worked examples and break-even points for per-domain pricing against a hypothetical per-mailbox plan, including aliases and multiple domains.
Gateway vs API-based tools
Some email security products connect to your mailboxes by API instead of sitting at the MX. Our guide to secure email gateways vs API email security compares the two designs.
Ready to look closer?
See why businesses choose iBlockSpam, the full feature list and pricing. If you already use another filter, read how to switch without losing email.
Related guides
Secure email gateway vs API-based email security: which do you need?
How an MX-based secure email gateway and API-based cloud email security each work, where each one wins, the trade-offs, and when to run both together.
9 min read Email security basicsHow do spam filters work?
How inbound spam filters decide what reaches your inbox: connection checks, reputation, SPF/DKIM/DMARC, content rules, attachment scans and quarantine.
9 min read Phishing & threatsHow to stop phishing emails in Microsoft 365
Set up Microsoft 365 anti-phishing policies, impersonation protection, external sender tags and user reporting, and decide when to add an email gateway.
9 min readLast updated: