Professional authenticated SMTP relay service. Bypass ISP port 25 blocks, improve email deliverability, prevent blacklisting with SPF/DKIM support and reputation management.
* All prices include UK VAT at 20% • Cancel anytime • No setup fees • Instant activation
SmartHost is an authenticated SMTP relay service for just £1 per month that ensures your emails reach recipients' inboxes instead of spam folders. Acting as an intelligent intermediary between your mail server and recipients, our SmartHost service bypasses ISP restrictions (port 25 blocks), improves deliverability through clean IP reputation, and prevents blacklisting. Perfect for businesses experiencing deliverability issues with direct SMTP sending, organizations whose ISPs block port 25, servers with poor IP reputation, transactional email systems, and anyone needing guaranteed email delivery. Works with all mail servers (Exchange, Postfix, Sendmail, Exim, qmail, MailEnable, SmarterMail) and requires only simple configuration changes to route outbound mail through our authenticated relay servers.
Most ISPs block outbound port 25 to prevent spam. Our service provides alternative ports (587, 465, 2525) allowing you to send email even with ISP restrictions.
Send emails from our professionally maintained IP addresses with excellent sender reputation. We actively monitor and maintain clean IPs that mailbox providers trust.
Secure authentication prevents unauthorized use and server abuse. Only authorized senders can relay mail through our service, protecting both you and our infrastructure.
Full support for SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) email authentication. Add our servers to your SPF record and use DKIM signing for maximum deliverability.
We actively monitor our IPs against all major blacklists and take immediate action if issues arise. Your sending reputation is protected by our reputation management team.
Significantly higher inbox placement rates compared to direct sending from shared hosting or dynamic IPs. Professional mail servers trust our relay infrastructure.
Works with your existing mail server software. Simply update SMTP relay settings to point to our service - no plugins, agents, or software installation required.
Compatible with all mail servers (Exchange, Postfix, Sendmail, Exim, qmail, Zimbra, MailEnable, SmarterMail) and email clients. Standard SMTP relay protocol.
Complete SmartHost SMTP Relay specs - £1/month
| Feature | Specification |
|---|---|
| Service Type | Authenticated SMTP relay (SmartHost) |
| SMTP Ports | 25, 587 (submission), 465 (SSL), 2525 (alternative) |
| Authentication | SMTP AUTH required (username/password) |
| Encryption | TLS/SSL supported on all ports |
| STARTTLS | Supported for opportunistic encryption |
| SPF Support | Full SPF support - add our IPs to your SPF record |
| DKIM Support | DKIM signing available for enhanced authentication |
| DMARC | Compatible with DMARC policies |
| IP Reputation | Professionally maintained clean IPs |
| Blacklist Monitoring | 24/7 monitoring of all major blacklists |
| Reverse DNS (PTR) | Properly configured PTR records for all IPs |
| Delivery Retry | Intelligent retry logic for temporary failures |
| Bounce Handling | Detailed bounce messages for failed deliveries |
| Rate Limiting | Reasonable limits to prevent abuse |
| IPv4 Support | Full IPv4 connectivity |
| IPv6 Support | IPv6 enabled for modern infrastructure |
| Compatible Mail Servers | Exchange, Postfix, Sendmail, Exim, qmail, Zimbra, MailEnable, SmarterMail, all others |
| Compatible Email Clients | Outlook, Thunderbird, Apple Mail, all SMTP-capable clients |
| Application Support | Web apps, CRM, ticketing systems, transactional email |
| Header Modification | Minimal - preserves original headers |
| Delivery Logs | Comprehensive logging available |
| Setup Time | 5-10 minutes (config change only) |
| Setup Complexity | Simple - update relay settings in mail server |
| Support | 24/7 technical support for configuration |
| Contract | Monthly, cancel anytime |
Instead of sending email directly from your server to recipients, you configure your mail server to send all outbound mail to our SmartHost relay. We authenticate your connection (username/password), accept the message, and intelligently route it to the recipient's mail server. To the recipient, the email appears to come from your domain - we simply act as the delivery mechanism.
Unlike open relays which anyone can abuse, our SmartHost requires SMTP authentication. You receive unique credentials (username/password) that your mail server uses to authenticate before sending. This prevents unauthorized use, protects our IP reputation, and ensures only legitimate mail flows through our service. Connections can be encrypted with TLS/SSL for additional security.
Most residential and business ISPs block outbound port 25 to prevent customers from running mail servers or sending spam. This blocks legitimate email too. Our SmartHost operates on alternative ports (587, 465, 2525) that ISPs don't block, allowing you to send email even with port 25 restrictions. We then deliver from our servers on port 25 to recipient mail servers.
Email deliverability depends heavily on sender IP reputation. If you send from shared hosting, dynamic IPs, or previously-abused addresses, mailbox providers may reject or spam-folder your mail. Our SmartHost IPs have excellent reputation maintained through active monitoring, abuse prevention, and relationships with mailbox providers. Your emails benefit from our clean reputation.
Modern email authentication requires SPF (authorizing which IPs can send from your domain) and DKIM (cryptographic signing). We provide our IP addresses for your SPF record and can sign messages with DKIM. When recipients check authentication, they see that your domain authorizes our servers and cryptographic signatures are valid - significantly improving inbox placement.
Stop emails going to spam - ensure inbox delivery
No contracts • Cancel anytime • 5-minute setup