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Free Mimecast alternatives: 1 app ranked by verified data

Facts checked Nov 8, 2026AppBreakup editorialHow we rank

1 of the 5 Mimecast alternatives we track can be used for free (free, open source, or with a free plan). Proxmox Mail Gateway ranks highest, with facts last verified Nov 8, 2026.

Quick comparison

#AppPricingVerified priceOpen sourcePlatformsVerified factsScore
1Proxmox Mail Gateway logoProxmox Mail GatewayOpen source€540/year per hostNoSelf-hosted, Linux4 of 461.8
  1. Proxmox Mail Gateway logo

    1. Proxmox Mail GatewayTop pick

    Best for: Companies running their own mail servers who want a packaged filtering gateway with a web UI

    Open sourceSelf-hosted, Linux

    61.8

    score / 100

    Why switch from Mimecast

    Self-hosted open-source gateway if you'd rather run filtering on your own servers.

    Pros

    • Complete gateway with web UI, quarantine and mail tracking
    • Bundles ClamAV antivirus and SpamAssassin
    • Open source and usable without a subscription
    • Subscriptions cover unlimited users and domains per host

    Cons

    • You run and maintain the gateway yourself
    • Support and the enterprise repository need a paid subscription
    • Relies on SpamAssassin, so it inherits its performance limits
    Visit Proxmox Mail Gateway Details and reviews
    How this score is calculated
    Editorial fit ×0.377
    Reviews ×0.363
    Clicks (90 days) ×0.150
    Freshness ×0.15100
    Votes ×0.150

    0 counted reviews, 0 up and 0 down votes. Full formula

    Is Proxmox Mail Gateway a good Mimecast alternative?

    Verified facts

    4 of 4 verified
    License
    GNU AGPLv3
    Checked Nov 8, 2026proxmox.com(opens source in a new tab)
    Starting price
    €540/year per host
    Checked Nov 8, 2026proxmox.com(opens source in a new tab)
    Users and domains
    Unlimited per subscription
    Checked Nov 8, 2026proxmox.com(opens source in a new tab)
    Filtering engines
    Postfix, ClamAV, SpamAssassin
    Checked Nov 8, 2026proxmox.com(opens source in a new tab)