Prerequisites
- How Zyntro Sends Your Email — How sending works before choosing a domain
Choosing Your Sending Domain
A decision you make once, and cannot undo from this screen.
What It Is
The sending domain is the domain part of the addresses Zyntro sends from. If you nominate comms.example.com, your senders are addresses such as [email protected], and that is what recipients see.
Zyntro recommends a dedicated subdomain of the domain you already own — comms.example.com rather than example.com — and the recommendation is stronger than a style preference.
Why It Matters
Setup asks you to publish an MX record on the sending domain itself, pointing mail for that domain at Zyntro. That record is required; Continue will not unlock without it.
An MX record is how the internet decides where mail for a domain should be delivered. So if you nominate the domain your business already receives email on, and then publish the record as instructed, mail for that domain stops going to your existing mailboxes and starts coming to Zyntro instead.
A dedicated subdomain has no mail of its own, so pointing its MX record at Zyntro costs you nothing. There is a second benefit too: sending reputation accrues per domain, so keeping Zyntro's traffic on a subdomain means a bad patch on either side cannot drag the other down.
How It Works
You enter the sending domain. Type it into Sending Domain on the setup screen.
Zyntro fills in the return path domain for you. As you type, Return Path Domain is filled in as inbound. plus your sending domain — enter comms.example.com and you get inbound.comms.example.com. This handles bounce reports. You can edit it, but it must stay on the same registered domain as the sending domain, and the screen warns you if it does not.
One sending domain per brand. The screen configures mail delivery for the brand you are working in. If you run several brands, each has its own setup.
The choice sticks. Once a domain is configured, this screen becomes the verification dashboard and the wizard is no longer reachable. There is no button to change or remove the domain, so if you need to move to a different one, contact Zyntro support.
Warning: Do not use a domain that already receives your email. The required MX record sends mail for the sending domain to Zyntro. Publish it on example.com and your everyday email stops arriving in your normal mailbox. Use a subdomain such as comms.example.com, which receives nothing today.
Examples
comms.example.com — recommended
A subdomain created specifically for this. It receives no mail today, so routing it to Zyntro changes nothing you rely on, and it keeps your platform sending reputation separate from your personal correspondence. Variations such as mail. or news. work equally well.
example.com — avoid
Your main domain almost certainly receives mail. Publishing the required MX record on it redirects that mail to Zyntro, and staff stop receiving messages sent to their own addresses. This is the single most damaging mistake available on this screen.
A separate domain you bought for outreach
A domain such as example-updates.com also works and receives nothing, so the MX record is harmless. The trade-off is recognition: recipients see a domain that does not obviously belong to you, which can cost you both trust and deliverability. A subdomain of your real domain is usually the better choice.
A domain on a two-part suffix, such as comms.example.co.uk
This works normally. Zyntro asks for the DMARC policy on the registered domain — example.co.uk in this case, so the record goes at _dmarc.example.co.uk. The other records sit on the sending domain and its return path as usual.
