SMTP Relay & Mail Server Hosting UK

DevOps services · United Kingdom

SMTP relay and mail server hosting for UK teams migrating off cPanel or Google Workspace, or setting up transactional email properly for the first time. We run self-hosted Mailu mailboxes on your own domain, plus a separate relay for transactional mail, with SPF, DKIM and DMARC configured and monitored so your messages land in the inbox instead of spam.

  • Mailu mailboxes hosted on your own domain
  • Separate relay keeps transactional mail reputation clean
  • SPF, DKIM and DMARC set up and monitored
Talk to an engineerSee our plans
  • VPS 1–8 h/month; dedicated 5–10 h/month depending on plan; GPU 10 h/month
    Included hours
  • Frankfurt, in the EU
    Data centre
  • Free white-glove migration, under 24 hours
    Migration
  • EUR invoicing, 20% UK VAT itemised
    Billing
01

Mailboxes and transactional mail, kept apart

We run Mailu as your self-hosted mailbox server, on your own domain, with webmail for your team, and we set up a separate SMTP relay for transactional mail from your application — password resets, invoices, order confirmations. Keeping them apart matters: one bulk campaign or a compromised account on the mailbox side shouldn't be able to damage the sending reputation your application depends on for password-reset emails to arrive.

  • Mailu mailboxes and webmail hosted on your own domain
  • Separate SMTP relay isolates transactional sending reputation
  • Migration from cPanel or Google Workspace mailboxes
  • Guided walkthrough of SPF/DKIM/DMARC records and sending limits
02

Best practices we apply

Most deliverability problems trace back to a handful of missing or misconfigured records, not a mysterious spam-filter grudge. We check for all of them on every relay we set up, and we leave the configuration documented so you understand why each record exists, not just that it's there. We also check sender reputation after go-live, since a clean DNS record set with a cold IP still lands in spam for the first few days.

  • SPF, DKIM and DMARC configured with reporting enabled
  • PTR/rDNS records set and IP reputation warmed up gradually
  • TLS enforced for delivery, with MTA-STS where supported
  • Mailbox and relay reputations kept fully separate
  • Rate limits and bounce handling configured, not left on defaults
03

The configuration guide

We hand you a written guide covering the DNS records, the SPF/DKIM/DMARC reporting set-up, and sending examples for your application, so your own developers can add new sending domains or debug a deliverability issue without waiting on us. It's the same reference we use internally when setting up a new relay, and it's linked from your client panel so it stays one click away when you need it.

04

How the included hours work

DevOps hours come with the plan: 1–8 hours a month on VPS tiers, 5–10 hours a month on dedicated servers depending on the plan, 10 hours a month on GPU servers. Use them for the initial Mailu and relay set-up, a migration from your current provider, or an investigation when deliverability drops. Request the work from the client panel under DevOps Services. Hours don't roll over month to month, so most teams use one month for migration and the next for DNS and reputation tuning.

How we work

  1. Request the work from the panel

    You describe your current mail set-up — cPanel, Google Workspace, or nothing yet — and propose a migration or set-up deadline.

  2. We scope the mailbox and relay split

    We confirm which domains need mailboxes, which need only a transactional relay, and the DNS changes required.

  3. We migrate and configure delivery

    We set up Mailu and the relay, migrate existing mailboxes, and configure SPF, DKIM and DMARC with reporting enabled.

  4. We hand over the configuration guide

    You receive the DNS records, the sending examples for your application, and the guide for adding new domains yourself.

Use cases

Professional-services firm leaving cPanel webmail

A consultancy on ageing cPanel webmail moves to Mailu with modern webmail and proper DKIM signing, after client emails started landing in spam folders.

SaaS startup separating transactional from marketing mail

A startup sending both marketing campaigns and password-reset emails from the same domain splits them onto separate relays, so a bulk-mail spam complaint stops affecting login emails.

E-commerce store scaling order confirmations

A retailer whose order-confirmation emails started bouncing during a sales spike gets rate limits and bounce handling configured properly on a dedicated transactional relay.

Technology stack

  • Mailu
  • Postfix
  • Dovecot
  • Rspamd
  • SPF
  • DKIM
  • DMARC
  • MTA-STS

Every subscription includes monthly DevOps, CyberSecurity and Programming hours: 1 h from the cPanel Advanced plan up, 1–8 h on VPS, 5–10 h on dedicated servers depending on the plan, and 10 h on GPU servers. Hours are requested from your client panel, don't roll over to the next month, and anything above the quota is accepted and billed separately.

Setup guide

The Mailu and SMTP relay setup guide: DNS records, SPF, DKIM and DMARC, then sending examples from your application and reputation checks.

Open the guide

Frequently asked questions

  • What is an SMTP relay and how does it work?

    An SMTP relay is a dedicated server that sends your application's outbound email — password resets, invoices, notifications — on your behalf, using its own warmed-up IP reputation. It's kept separate from regular mailbox traffic so one doesn't damage the deliverability of the other.

  • Do I need an SMTP relay if I self-host my mail server?

    Usually yes, for transactional mail specifically. A self-hosted mailbox server handling day-to-day staff email has a different sending pattern and risk profile to your application's automated emails — separating them protects both from each other's reputation problems.

  • How do I stop my emails being marked as spam?

    Correctly configured SPF, DKIM and DMARC records are the baseline, alongside a warmed-up sending IP and consistent sending volume. We set up and monitor all three when we configure your relay, and DMARC reporting shows you exactly what's failing if deliverability drops.

  • Mailu vs mailcow vs Mail-in-a-Box — which do you run?

    We run Mailu, which we chose for its clean Docker-based deployment and active maintenance. Functionally it competes closely with mailcow; the meaningful difference for you is that our team operates and patches it as part of your included hours, not you.

  • Can Mailu relay through an external SMTP service for deliverability?

    Yes — Mailu can relay outbound mail through a third-party sending service if you want its deliverability reputation on top of self-hosted mailboxes. We can set this up as an alternative to, or alongside, our own transactional relay, depending on your volume.

  • Can you migrate our mailboxes from cPanel or Google Workspace?

    Yes, migration is free and handled white-glove, typically completed in under 24 hours. We plan the cutover to minimise the window where mail could be missed, and verify DNS and DKIM before switching MX records over.

Emails landing in spam, or migrating off cPanel mail?

Tell us your current mail set-up and we'll design the Mailu and relay split, with SPF, DKIM and DMARC configured properly from the start.

Talk to an engineerSee our plans

Guides for UK businesses