Email Deliverability Infrastructure and Best Practices

Q: What is email deliverability?

Email deliverability is whether the email you send reaches the recipient's inbox rather than the spam folder or a silent block. It is distinct from delivery rate, which only says whether the message was accepted.

Q: What are the most important email deliverability best practices?

Authenticate your domain with SPF, DKIM, and DMARC; only email people who explicitly opted in; keep your list clean; send relevant mail that earns engagement; and send from a reputable, warmed sending domain.

Q: How do I improve email deliverability?

Start with authentication, then fix list hygiene by removing bounces and dormant contacts and requiring explicit opt-in. Warm new sending domains gradually, keep complaints low, use a replyable From address, and track inbox placement.

Q: Does Loops handle deliverability for me?

Loops handles the infrastructure-heavy parts: SPF, DKIM, and MX records, sending-domain verification, managed sending infrastructure, spam-filter checks, bounces, complaints, and suppressions. You still own consent, segmentation, and content.

Email deliverability is whether a message reaches the intended inbox rather than being rejected or filtered to spam. It depends on the sending identity, transport infrastructure, domain or IP reputation, audience quality, and the message itself.

Resources

Use the map below to find the owner of each layer and the evidence worth checking. If delivery changes, start with authentication and provider events.

Then inspect complaints, bounces, recent volume changes, audience source, and the final message. This guide covers product, lifecycle, and transactional email from software products.

Deliverability infrastructure map

Deliverability crosses several systems and owners. This map shows where to look first and what to collect.

Layer

Primary owner

Verify

Sending identity

Sender and provider

SPF and DKIM results, plus DMARC alignment

Transport

Provider

TLS, acceptance, queues, and delivery events

Reputation

Shared

Complaints, bounces, deferrals, and blocks

Audience and consent

Sender

Signup source, suppressions, and inactivity policy

Message and stream

Sender

Purpose, sender, unsubscribe, HTML, and links

Monitoring

Shared

Provider logs, Postmaster Tools, and DMARC reports

How deliverability is measured: delivery rate vs inbox placement

Deliverability outcomes happen at two stages. Delivery rate reports whether the receiving server accepted the message. Inbox placement reports where an accepted message landed: the inbox, the spam folder, or a category such as Promotions. Track both, because a high acceptance rate can sit alongside spam placement. Read our tips to improve your inbox placement and why emails go to spam when placement slips. When either moves, inspect SMTP responses and what SMTP error codes mean, along with complaint data and provider logs, and run controlled inbox tests before changing anything.

Email authentication: SPF, DKIM, and DMARC

SPF, DKIM, and DMARC let a receiver tie a message to the domain shown to the recipient. Google and Yahoo require bulk senders to authenticate with all three, keep complaint rates low, and offer one-click unsubscribe. Here is how SPF, DKIM, and DMARC work in Loops: SPF lists the systems allowed to send for an envelope domain, DKIM signs the message so a receiver can verify it was not altered, and DMARC checks that the SPF or DKIM domain aligns with the visible From domain. Start DMARC at p=none, read the aggregate reports until every legitimate sender aligns, then move to quarantine or reject.

If you send through Loops, most of this is filled in for you. Loops generates the exact SPF, DKIM, and MX records for your domain and places its SPF record at an envelope subdomain such as envelope.yourdomain.com so it will not collide with an existing SPF record. You can also send from a subdomain instead of your root domain. Copy the records into your registrar once when you add your sending domain, then check your DNS records and click verify. DNS can take up to an hour to propagate.

Sender reputation

Mailbox providers evaluate sending history at the domain and IP level. Complaints, hard bounces, invalid recipients, sudden volume changes, and repeated mail to inactive recipients all damage that history. Authentication establishes identity, but it does not create a good reputation on its own. Reputation is earned by consistent mail that recipients want. Learn how to build your sender reputation over time.

Warmup and sending volume

A new domain or dedicated IP has no history, so ramp it. Start with the recipients who most recently asked for the mail, raise volume in controlled steps, and slow down when deferrals, bounces, or complaints climb. A dedicated IP gives one sender full control of its IP history but needs enough steady mail to hold it, so a managed shared pool is often the better default for lower or uneven volume. There is no universal message count that makes a dedicated IP correct.

For specific cases, see sending to a large new audience, moving to a new sending domain, and sending from more than one domain.

List hygiene and consent

List quality starts with permission. Every address should have a clear source, a message type it can receive, and a suppression path. Purchased or scraped lists create complaint and spam-trap risk that authentication cannot repair. Use confirmed opt-in where a form is easy to abuse, reduce your product email bounce rate by suppressing hard bounces and complaints immediately, and keep your list clean by holding consent and unsubscribe state in one source of truth.

If you send to Apple relay users, register your domain so you can reach Apple Hide My Email addresses.

Engagement signals and content

Once identity and audience quality check out, look at the message itself. Complaints, unsubscribes, replies, clicks, and product activity reveal a mismatch between the audience and the send. Treat opens as directional, not exact; here is why open rates are unreliable.

Use a recognizable From name, add a sending avatar so recipients know you, and a monitored reply address. Give marketing mail a visible unsubscribe link plus a one-click List-Unsubscribe header, and keep links on the sending brand, since shortened YouTube links flagged in Gmail can hurt placement. Test the final MIME message rather than the editor preview.

Monitoring and tools

Deliverability is a running measurement, not a one-time setup. Watch complaint rate, bounce responses, and delivery events per stream, and read the signals your mailbox providers publish. Gmail does not report spam complaints back to Loops, so set up Google Postmaster Tools to see how Gmail scores your sending.

See how Loops monitors your sends, and browse email deliverability tools to round out your stack.

What Loops handles, and what you own

Loops manages the sending service and generates the message sent to the receiving provider. The sender decides who receives it, why they receive it, and whether it is transactional or marketing email.

Loops supplies sending-domain records, verifies the configured domain, and sends over managed infrastructure. It automatically suppresses hard bounces and complaints, and webhooks expose delivered, bounced, and complaint events for monitoring.

DNS ownership, DMARC policy, consent, segmentation, and message content stay with the sender.

Transactional email deliverability for SaaS

Keep account-critical messages separate from promotional campaigns in templates, triggers, monitoring, and rate controls. Verification links, password resets, receipts, billing notices, and security alerts should have one clear purpose and a recognizable sender.

Leave unrelated promotions out of required mail. Monitor transactional latency, bounce responses, and delivery events separately.

A campaign problem should not hide an authentication failure or a delayed account email.

If your recipients use shared mailboxes, follow the guide on delivering transactional email to group inboxes.