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Connect Sendy to Mailyte

Sendy is a self-hosted newsletter app that sends through a sending server you configure. This guide points Sendy's SMTP sending server at Mailyte SMTP Send so your campaigns relay through your verified domain.

Read this first

Your domain must be verified (SPF + DKIM + DMARC green), the AUP accepted, and prepaid credits on the account before a live credential is issued. See Send Marketing & Bulk Email for the sending requirements, bounce/complaint limits, and warm-up.

Before you start

  • A running Sendy install (Sendy 6+ supports SMTP as a sending server).
  • A verified sending domain in Mailyte — for example acme.com, ideally a marketing subdomain such as news.acme.com.
  • A Mailyte login with access to the Sending area of the dashboard.

Step 1 — Create an SMTP credential in Mailyte

In the Mailyte dashboard, open Sending → SMTP Credentials and create a credential scoped to your sending domain. Give it a name you'll recognise (for example sendy), and — for marketing — start with conservative hourly_limit / daily_limit values that match your warm-up schedule.

When the credential is created, Mailyte shows the secret exactly once. Copy it now; it is stored only as a hash and cannot be retrieved again (you can always rotate it later).

You now have:

Field Where it comes from
Username Generated by Mailyte, e.g. acme-com-smtp-x7k2m9
Password The secret shown once at creation

Lock the credential to Sendy's IP

A credential can carry an IP allowlist. If your Sendy server has a fixed IP, add it to the credential's allowlist so a leaked secret can't be used from anywhere else.

Step 2 — Point Sendy's sending server at Mailyte

In Sendy, go to Settings and set the SMTP sending server details:

Sendy field Value
Sending method / server SMTP
Host smtp.acme.com (if you've pointed that record at Mailyte) or your Mailyte mail hostname, e.g. mail.yourdomain.com
Port 587 (STARTTLS) or 465 (SSL/TLS)
Encryption STARTTLS on 587, SSL/TLS on 465
SMTP username the credential username, e.g. acme-com-smtp-x7k2m9
SMTP password the secret from Step 1

Then set the From address on your brand/list to an address at the credential's domain — for example news@acme.com.

The From address must match the credential's domain

A credential scoped to acme.com may only send From: addresses at acme.com (or its subdomains). Sender-login mismatch is enforced on ports 587 and 465, so a mismatched From address is rejected at submission.

Sendy rewrites links for its own open and click tracking. Mailyte's content filter can also inject an open pixel and rewrite links — running both double-wraps every link and skews both sets of stats.

Pick one owner of tracking:

  • Keep Sendy's tracking (recommended for campaigns): turn off Mailyte tracking on this credential — set the per-credential tracking toggle to off in the credential's settings. Sendy's opens/clicks are then the source of truth.
  • Prefer Mailyte's tracking: leave the credential's tracking on and disable Sendy's link/open tracking instead.

Do not leave both on.

Step 4 — Send a test campaign

Create a small test list of addresses you control and send a campaign. Confirm:

  • The message arrives and shows dkim=pass in its headers.
  • Links resolve correctly (proof you're not double-wrapped).
  • The message carries an unsubscribe option — Mailyte injects a List-Unsubscribe one-click header automatically unless Sendy already sends its own, but you must still include a visible unsubscribe link in the body (Sendy's [unsubscribe] tag).

Where bounce and complaint handling comes from

With plain SMTP, Sendy has no native way to process bounces — Mailyte handles this for you, server-side:

  • A hard bounce or spam complaint auto-suppresses that recipient on your organization's unified suppression list.
  • Any later send to a suppressed address is rejected with a permanent 5.7.1 at the SMTP layer, whether or not Sendy excluded it.
  • Sustained bounce (>5%) or complaint (>0.3%) rates auto-pause the credential and notify you — see Send Marketing & Bulk Email.

Watch your delivery, bounce, and complaint numbers in the Mailyte Deliverability Center and the credential's usage view rather than relying on Sendy alone. Before your first Sendy campaign, import your previous ESP's bounce/unsubscribe list into Mailyte's suppressions so you never re-mail an address that already went bad.