Deliverability Best Practices

Deliverability isn't one setting — it's a handful of practices that add up. These are grounded in what's actually configurable in Mersal, plus a couple of general sending practices worth following even though the platform doesn't enforce them.

Set up DKIM for your sending domain

If you're sending email, DKIM is the single highest-leverage thing you can configure. Mersal generates the DNS records your domain needs; once you add them at your DNS provider and verify the domain from the dashboard, your outgoing mail is cryptographically signed as coming from your domain — which meaningfully improves inbox placement instead of landing in spam. See Setting Up DKIM and Tracking Domains for the full walkthrough.

Use a branded tracking domain

Open and click tracking links default to a generic shared domain. Setting up your own tracking domain — configured alongside DKIM when you add a sending domain — means the links in your emails match your brand instead of a third-party domain. Beyond looking more trustworthy to recipients, a domain-matched link is generally viewed more favorably by spam filters than a link pointing at a domain shared across many unrelated senders.

Warm up new gateways gradually

A brand-new sending domain, SMTP account, SMS provider connection, or WhatsApp number has no sending history. Sending a large volume immediately is more likely to trigger spam filtering or provider-side throttling than the same volume sent gradually over days or weeks while the gateway builds a track record. If you're migrating an existing list to a new gateway, ramp up rather than sending your full list on day one.

Keep your contact list clean

A list full of stale, mistyped, or badly formatted numbers drags down your delivery rate and wastes sending allowance. Rather than manually cleaning a spreadsheet before import, let Mersal's Excel import do it for you — it automatically normalizes and cleans phone numbers (fixing formatting, spacing, and missing country codes) and upserts existing contacts instead of creating duplicates. See Importing Contacts from Excel.

Respect rate-limit presets

Every gateway has rate-limit presets — per-minute, per-hour, and per-day caps on how fast messages actually go out. These exist for a reason: sending as fast as technically possible right after connecting a new gateway is one of the fastest ways to get it flagged, particularly for an Android SIM Gateway, where unusual sending speed can get a physical SIM flagged by the carrier. Leave presets at a conservative level when a gateway is new, and only increase them once you have a sending history to justify it.

Where to go next

• Setting Up DKIM and Tracking Domains — step-by-step domain setup.
• Gateways Overview — how gateways and their rate-limit presets work across channels.
• Message Delivery Issues — a checklist for when something isn't arriving despite following these practices.