ImprovMX

ImprovMX is a custom-domain email forwarding service with API controls and an option to send mail from your domain. It suits individuals and organizations that want flexible routing without running their own mail infrastructure. Its strongest case is domain forwarding with room to grow; its clearest drawback is that messages bounce after a domain exhausts its daily quota.

Overview

ImprovMX routes mail sent to custom-domain addresses to existing inboxes, and paid plans add SMTP sending alongside the JSON Send API. Catch-all and regex aliases, configurable rules, and multiple destinations per alias make it more adaptable than a basic forwarder. The free tier includes API access, but SMTP is reserved for paid plans.

Delivery logs show operational details such as sender, destination, event, server response, and status code, but not message content. Standard log retention is seven days; paid plans offer longer retention, up to 180 days or unlimited depending on the plan. ImprovMX says it encrypts stored data, uses TLS for SMTP connections that support it, conducts annual independent penetration tests, complies with GDPR, and does not sell data. It does not pursue SOC 2 or ISO 27001 certifications, so organizations requiring either should look elsewhere.

Key features

Routing and sending

Catch-all forwarding handles addresses across a domain, while regex aliases and rules allow more specific routing. Sending one alias to several destinations is useful when separate inboxes need the same incoming mail. The plan caps on aliases and rules become important for domains with many addresses or complex routing. SMTP and the JSON Send API enable outbound mail from a custom domain, but only paid plans include SMTP.

Administration and setup

The REST API can manage domains and aliases programmatically, making it a practical option for projects that automate address administration. Premium users can use one-click DNS setup with supported providers; ImprovMX says the feature now works with most providers. Setup guides cover services including Cloudflare, Namecheap, DigitalOcean, Vercel, and Netlify, while SMTP guides cover Gmail, Apple Mail, and Thunderbird.

Quota behavior

Daily forwarding limits are a meaningful reliability constraint, not merely an account-management detail. When a domain reaches its quota, ImprovMX stops processing its mail until 00:00 UTC; mail received in the meantime is bounced to senders. That behavior may be acceptable for low-volume projects, but it is a poor fit for an address where uninterrupted receipt is essential unless the plan's capacity is comfortably above expected traffic.

Pricing

The Free plan costs nothing and covers one domain, 25 aliases, 500 forwarded emails per day, seven-day email logs, API access, standard email and chat support, and a 99% uptime guarantee. It is a useful starting point for a low-volume domain, but the modest daily cap and lack of SMTP make it limiting for active business mail.

Light costs $50 a year, billed yearly. It allows up to five domains, 25 aliases per domain, five rules per domain, 5,000 forwarded emails per day, and 750 SMTP sends per month. This is the lowest-cost paid choice for a small setup needing SMTP, though the send allowance and rule cap constrain heavier use.

Premium costs $9 a month, billed monthly. It raises capacity to 30 domains, 100 aliases and 10 rules per domain, 5,000 forwarded emails per day, and 12,000 SMTP sends per month. It also adds webhooks, email logs up to 180 days, and priority email and chat support. This suits users who need substantially more aliases, automation hooks, or support priority than Light provides.

Pro costs $24 a month, billed monthly. It supports up to 100 domains, 200 aliases and 50 rules per domain, 15,000 forwarded emails per day, and 60,000 SMTP sends per month. The larger routing and sending allowances make it the better fit for multi-domain operations with higher traffic.

Enterprise has custom pricing and offers unlimited domains, aliases, forwarding, and SMTP sends, plus a dedicated account manager and support SLAs. It is aimed at organizations that need those terms rather than a fixed self-serve allowance. Across paid tiers, choose by both forwarding and SMTP volume: ample capacity in one does not remove the other plan limits.

Platforms

ImprovMX is available on the web and through an API. It is a service for routing domain email rather than a device-specific mail client; the SMTP guides support sending through Gmail, Apple Mail, and Thunderbird.

Who it's for

ImprovMX is a good fit for domain owners, small businesses, and side projects that want aliases, routing rules, multi-destination forwarding, and programmatic control in one service. The free plan can cover modest forwarding needs, while Light is a low-cost step up for small volumes that need SMTP. Choose Premium or Pro when domain, alias, rule, or sending capacity justifies the higher monthly price. It is less suitable when bounced messages at a quota boundary are unacceptable or a procurement process requires SOC 2 or ISO 27001.

Pros and cons

• Flexible routing: Catch-all and regex aliases, rules, and multiple destinations handle more cases than simple one-to-one forwarding.
• API access on Free: Automation is possible without first moving to a paid tier.
• Paid outbound sending: SMTP and the JSON Send API let users send from a custom domain, with plan-specific monthly SMTP allowances.
• Operationally useful logs: Delivery events expose routing and server outcomes without logging email content; retention ranges from seven days to longer paid-plan periods.
• Hard quota stop: Once a domain reaches its daily forwarding limit, later mail is bounced until the UTC reset, which risks missed messages.
• Limited Free capacity: One domain and 500 forwards per day can be restrictive for busier use, and SMTP is not included.
• No SOC 2 or ISO 27001: Organizations that require either certification cannot treat ImprovMX's other security measures as a substitute.

Alternatives

Email Forwarding Services is a useful starting point for comparing the category. Consider Forward Email if you want a service built with open-source software and broader platform coverage, including self-hosting. Choose Haltman mail-forwarding-core if you need unlimited forwarding rules, users, addresses, domains, and emails at no cost and forwarding alone is enough.

Forward has a Free tier with the same one-domain, 25-alias, 500-forward-per-day, and seven-day-log allowances, so it is worth comparing if those caps suit you. MailerZ may suit a user who prefers a message store and a free tier with three aliases, but its free plan disables send-as, SMTP, and API access. DNSExit Email Forwarding is an alternative if you want a web-based forwarding service, including a free plan for domains registered through DNSExit.

EForw is worth considering if unlimited catch-all aliases and SPF, DKIM, and DMARC passing on a free plan are priorities. InboxMail offers a different mix of email and AI features, with a free plan that includes one custom domain and unlimited aliases. KaiMail is another freemium option for custom-domain email, with a free plan limited to one mailbox and 300 emails per month.

Verdict

Choose ImprovMX if you want flexible custom-domain forwarding, API-managed aliases, and a path to paid SMTP sending without operating your own mail system. Its routing controls and tiered capacity are compelling for domains with moderate, predictable traffic. Look elsewhere if quota-triggered bounces pose too much risk or formal SOC 2 or ISO 27001 certification is a requirement.