Proxmox Mail Gateway + SmarterMail Enterprise: Corporate Email Without the Per-Seat Hyperscaler Tax
Shared hosts break email deliverability by putting your mailboxes on the same IP as public websites—while Microsoft 365 and Google Workspace quietly ratcheted per-user fees up to $12–$36/seat every month.
Since 2007, GreenTree has engineered a cleaner, faster alternative: we route all inbound and outbound mail through our dedicated 8-stage Proxmox Mail Gateway cluster (mx.greentreemail.com)—blocking 10M+ spam, phishing, and ransomware messages per month at a 0.003% false-positive rate—before delivering clean messages to SmarterMail Enterprise (east.greentreemail.com) with full Exchange ActiveSync, MAPI, and shared groupware starting at just $4 to $8/mailbox.
Three Enterprise Mailbox Tiers — Protected by Proxmox Gateway at Every Level
Every mailbox includes full `mx.greentreemail.com` 8-stage inbound/outbound filtering, 2048-bit DKIM signing, strict SPF/DMARC alignment, and white-glove migration from your current provider.
SmarterMail Business Core
Operational staff, field technicians, and role accounts requiring clean, ad-free corporate email with industrial spam defense.
- Protected by Proxmox Mail Gateway (mx.greentreemail.com) inbound/outbound scrubbing
- Full SPF, DKIM (2048-bit), and DMARC alignment engineered by our team
- Lightning-fast SmarterMail Enterprise webmail client with shared calendars & contacts
- Zero data mining, zero advertising, 100% US-governed storage
SmarterMail Enterprise + Exchange ActiveSync
Executives, sales leaders, and teams needing native real-time push synchronization across iPhone, Android, Outlook Desktop, and macOS.
- Native Microsoft Exchange ActiveSync (EAS) & MAPI for zero-plugin Outlook & mobile sync
- Real-time push mail, shared corporate calendars, global address lists (GAL), and task delegation
- Proxmox Mail Gateway zero-hour virus, phishing, and RBL quarantine digest controls
- White-glove mailbox migration from Microsoft 365, Google Workspace, GoDaddy, or legacy IMAP
SmarterMail Executive & Compliance Vault
Legal, financial, real estate, and industrial executives requiring deep mailbox capacity and retention governance.
- 100 GB primary NVMe mailbox allocation with server-level message retention policies
- Dedicated outbound IP reputation governance & custom rDNS/PTR verification
- Priority administrative support for employee onboarding/offboarding and litigation holds
- Continuous DNSBot.app monitoring of your domain’s MX, SPF, DKIM, and DMARC records
How Our 8-Stage Proxmox Mail Gateway Scrubs Every Message Before It Reaches Your Team
Instead of letting spam and ransomware land in a user’s Junk folder where a single click can compromise your network, our perimeter gateway inspects and drops threats at the network edge.
Postscreen Protocol Checks & Real-Time Blackhole Lists
Before a remote mail server even speaks SMTP to our cluster at mx.greentreemail.com, Postscreen drops zombie botnets and checks Spamhaus Zen, Barracuda, and custom reputation feeds.
Strict TLS 1.3, SPF Hard-Fail, 2048-Bit DKIM & DMARC
We verify sender envelope authenticity against strict SPF policies, validate 2048-bit RSA cryptographic DKIM signatures, and enforce DMARC alignment to block domain spoofing and CEO fraud.
ClamAV Antivirus, Attachment Sandboxing & Heuristics
Every inbound attachment and HTML body is scanned in real time for ransomware macros, phishing links, and zero-hour malware signatures before it can reach a user inbox.
Sub-50ms Delivery to east.greentreemail.com (EAS / MAPI)
Verified clean mail is delivered over our private backbone to SmarterMail Enterprise—syncing contacts, shared calendars, and folders instantly to Outlook, iPhone, Android, and webmail.
Microsoft 365 / Shared Host Email vs. GreenTree Proxmox + SmarterMail
| Evaluation Factor | Hyperscaler Per-Seat Tax / Shared cPanel Mail | GreenTree Proxmox + SmarterMail Enterprise |
|---|---|---|
| 3-Year Cost for a 25-Person Company | ✗ $10,800 – $27,000+ on Microsoft 365 / Google Workspace once per-seat add-ons, archiving, and security tiers are tacked on. | ✓ $3,600 – $7,200 total ($4 to $8/mailbox/mo) with Proxmox 8-stage gateway security included at zero extra per-seat tax. |
| Outbound IP Reputation & Deliverability | ✗ Shared cPanel/web hosts put your email on the same IP as public websites—causing constant Gmail/Outlook spam-folder blocks. | ✓ 100% dedicated mail clusters (mx.greentreemail.com & east.greentreemail.com) isolated from all web hosting traffic. |
| Inbound Spam & Phishing Defense | ✗ Basic default filtering unless you pay extra per user for Defender / advanced threat add-ons. | ✓ Industrial 8-stage Proxmox Mail Gateway blocking 10M+ threats/mo at a verified 0.003% false-positive rate. |
| Support When an Important Email Goes Missing | ✗ Impossible to get a human engineer to trace a real-time SMTP log in Microsoft 365 or Google. | ✓ Call or email our Southbury, CT desk and we will pull the exact line-by-line Proxmox/SmarterMail SMTP transaction log in minutes. |
Frequently Asked Questions About Enterprise Email
Will our team lose their existing emails, folders, contacts, or shared calendars when switching from Microsoft 365 or Google Workspace?
No. We perform a complete server-to-server mailbox migration covering all historical emails, folder structures, contacts, and calendars—and help your team connect Outlook, Apple Mail, iPhones, and Android devices via native Exchange ActiveSync (EAS), MAPI/EWS, or IMAP.
Why does separating email hosting from web hosting matter so much?
On standard shared hosts, your company’s email shares an IP address with PHP contact forms and websites. The moment one website on that server gets compromised or sends a burst of mail, Gmail and Microsoft block the entire IP—and your invoices and proposals stop reaching customers. By isolating all email on mx.greentreemail.com and east.greentreemail.com, your mail reputation stays pristine.
Can we mix and match $4, $8, and $14 mailbox tiers within the same company domain?
Yes! Unlike Microsoft and Google who force every employee onto expensive licensing tiers, you can put field technicians or role accounts on $4/mo Core IMAP mailboxes (25GB) while placing executives and project managers on $8/mo Enterprise ActiveSync (50GB) or $14/mo 100GB Vault mailboxes.
Do you configure our SPF, DKIM, and DMARC records for us?
100% included. Since Google and Yahoo now strictly enforce SPF, 2048-bit DKIM, and DMARC policies for bulk and commercial senders, we engineer, test, and monitor your DNS authentication records directly.