7 Tips to Increase Email Deliverability

Email deliverability is the practice of getting legitimate messages to land in the inbox instead of the spam folder, and it depends on trust signals that mailbox providers watch closely. Start by authenticating your sending domain with SPF, DKIM, and DMARC, then protect your sender reputation by using permission-based signups, removing hard bounces, and pausing long-unengaged contacts. Keep emails easy to parse with a clear From name, sensible text-to-image balance, and subject lines that match the message, and send at a steady cadence to the right segments so engagement stays strong. The non-obvious trap is how fast one messy list upload can outweigh great copy.

Email domain authentication with SPF, DKIM, and DMARC

SPF records for your sending sources

SPF (Sender Policy Framework) tells inbox providers which servers are allowed to send email for your domain. Without it, your messages can look spoofed, even if you are a legitimate sender.

Create an SPF record that includes every real sending source you use, like your marketing platform, CRM, support desk, and any transactional service. Keep it tight. A common mistake is stacking multiple SPF TXT records. Most domains should have one SPF record that lists all approved senders. Also watch your “DNS lookups” count. Overly complex SPF setups can fail in ways that are hard to notice until deliverability drops.

DKIM signing to protect message integrity

DKIM (DomainKeys Identified Mail) adds a cryptographic signature to each message, proving it was sent by an authorized system and was not altered in transit. In practical terms, DKIM helps your domain build reputation and reduces the chances that mailbox providers treat your email as suspicious.

Your sending platform (including Mailscribe) will typically provide DKIM DNS records to add, often as CNAMEs. After publishing them, confirm that outgoing messages show a DKIM “pass” result. If you rotate keys, do it on a schedule and avoid making changes right before a major campaign.

DMARC policy, reporting, and alignment

DMARC ties SPF and DKIM together and tells mailbox providers what to do if authentication fails. It also adds reporting, which is one of the fastest ways to spot spoofing or misconfigured senders.

DMARC works best when your From address domain “aligns” with either SPF or DKIM. Alignment sounds technical, but the goal is simple: the domain your subscribers see should match the domain that proves authenticity.

DMARC p=none to quarantine to reject progression

If you are new to DMARC, start with p=none to collect reports without impacting delivery. Once you confirm all legitimate sources authenticate correctly, move to p=quarantine (send suspicious mail to spam) and then p=reject (block it). This progression protects your brand from spoofing while keeping your real campaigns stable.

Email list hygiene habits that reduce bounces and complaints

Remove hard bounces and role-based addresses

List hygiene starts with removing addresses that should never be mailed again. Hard bounces usually mean the mailbox does not exist, the domain is invalid, or the address is permanently blocked. Keeping these on your list signals poor list quality and can drag down deliverability fast. In Mailscribe, treat hard bounces as an automatic suppression, not a “try again later.”

Also be cautious with role-based addresses like info@, sales@, support@, and admin@. Some are real, but many are shared inboxes or heavily filtered. They tend to generate lower engagement and more spam complaints. If you must mail them (for example, B2B accounts), segment them separately and mail less often.

Prune inactive subscribers on a schedule

Inactivity is not just a revenue problem. It is a deliverability problem. Mailbox providers use engagement signals, and a list full of people who never open, click, or reply can make your future sends look unwanted.

Set a simple pruning cadence. For many teams, reviewing inactivity every 30 to 90 days is enough. Create a segment like “no opens or clicks in 90 days” (adjust based on your typical buying cycle), then either reduce frequency or move those contacts into a re-engagement track. If they still do not respond, sunset them from regular campaigns and keep them suppressed unless they re-subscribe or update preferences.

Use confirmed opt-in where it fits

Confirmed opt-in (also called double opt-in) asks new subscribers to click a confirmation link before they are added to your marketing list. It reduces typos, bots, and fake signups, which means fewer bounces and fewer spam complaints later.

It is not mandatory for every program, but it is a strong fit when you run giveaways, paid ads to lead magnets, or any signup channel that attracts low-intent traffic. If you choose single opt-in for conversion reasons, offset the risk with tighter validation, a clear welcome email, and early engagement prompts (like a “reply and tell us what you want” question).

Engagement-based segmentation to boost inbox placement

Segment by recent opens and clicks

Mailbox providers pay attention to engagement patterns. So one of the simplest deliverability wins is to stop treating your whole list the same. Build segments based on recent activity, then send your most important campaigns to the people most likely to interact.

A practical starting point is three buckets:

• Hot: opened or clicked in the last 7 to 30 days
• Warm: engaged in the last 31 to 90 days
• Cold: no engagement in 90+ days (or longer if your sales cycle is long)

Send more frequently to Hot, less frequently to Warm, and be cautious with Cold. This keeps your overall engagement rate healthier, which helps inbox placement over time.

Send re-engagement campaigns before sunsetting

Before you suppress inactive subscribers, give them a clear, low-pressure chance to stay. A good re-engagement campaign is short and specific. It reminds them what they signed up for, offers an easy preference update, and makes it simple to opt out.

Keep it to one to three emails over 7 to 14 days. If there is no open, click, or reply after that, move them out of regular sends. This “re-engage then sunset” approach protects deliverability because you are not repeatedly sending to people who are showing zero interest.

Encourage replies and adds-to-contacts

Not all engagement is equal. Clicks are helpful, but replies are a particularly strong signal that real humans want your emails. When it fits your brand, ask a simple question and invite a reply, especially in your welcome sequence and re-engagement emails.

You can also ask subscribers to add you to their contacts or safe sender list. Do this lightly, as a helpful tip, not a demand. For example: “If you want to make sure you never miss updates, add this address to your contacts.” Small steps like these can reduce “missing inbox” issues caused by aggressive filtering, especially for new domains.

Consistent sending frequency and volume that protects reputation

Avoid sudden spikes in sends

Email reputation is built on patterns. If you normally send 5,000 emails a week and suddenly send 80,000 tomorrow, that looks risky to mailbox providers, even if your list is permission-based. Sudden spikes also increase the chance you hit spam traps, outdated addresses, or disengaged subscribers all at once.

Aim for predictable volume. If you need to scale up, do it in steps. For example, increase send volume gradually over several campaigns, starting with your most engaged segment first. In Mailscribe, this is easy to manage with engagement-based segments and scheduled sends, so you can ramp volume without flooding your whole list.

Warm up new domains and dedicated IPs

New sending domains and new dedicated IPs start with little or no reputation. Warming up is the process of proving you are a consistent, wanted sender over time. The safest approach is to begin with highly engaged subscribers, keep complaint rates low, and expand slowly.

A warm-up plan does not need to be complicated, but it should be deliberate:

• Start with your most recent openers and clickers.
• Send smaller batches at a steady cadence.
• Increase volume gradually while monitoring bounces, complaints, and placement.

If you are switching platforms or changing your From domain, expect a transition period. Plan key launches around it instead of assuming day-one performance will match an older, established setup.

Balance promotional and value emails

Deliverability improves when subscribers regularly find your emails useful. If most of your sends are “buy now” messages, engagement often drops, and spam complaints can rise. A healthier mix includes value-led emails that earn opens even when people are not ready to purchase.

Value can be simple: a short tutorial, a checklist, a product-use tip, a customer story, or an update subscribers genuinely asked for. The goal is not to avoid promotions. It is to make sure your list has a reason to keep opening, so your promotional emails have a better chance of landing in the inbox and converting.

Email content and formatting that avoids spam filters

Write subject lines that match the email body

Spam filters and humans react badly to bait-and-switch. If your subject line promises one thing and the email delivers something else, opens might happen once, but trust drops fast. That trust loss shows up as deletes without reading, low clicks, and more complaints, all of which hurt deliverability.

Keep subject lines specific and honest. Make sure the first sentence of the email clearly supports the promise in the subject. If you use personalization, use it when it adds clarity, not as a gimmick. Also avoid misleading “Re:” or “Fwd:” style lines unless the message is actually part of a real thread.

Keep links, images, and HTML clean

Messy formatting is a common deliverability problem. Simple, clean HTML is easier for mailbox providers to scan and for subscribers to read across devices.

A few practical rules:

• Do not use link shorteners for marketing emails unless you truly need them. Branded, readable URLs are safer and build trust.
• Keep the number of links reasonable, and make sure they go to domains you control or well-known destinations.
• If you use images, include real text too. Image-only emails often perform poorly and can be filtered more aggressively.
• Use standard fonts, clear spacing, and accessible color contrast. Over-designed templates can break in dark mode or clip in some inboxes.

Before a big campaign, send a test to a couple of real inboxes (Gmail, Outlook, Yahoo) and check that the layout and links behave normally.

Include a clear plain-text version

Many mailbox providers and security tools still evaluate the plain-text part of an email. Subscribers also use text-only views in some clients. A missing or sloppy plain-text version can look like low-quality bulk mail.

Your plain-text version should be readable on its own. Include the main message, a clear call to action with a full URL, and your physical address and unsubscribe language where required. If you write in a simple, conversational style first, it is usually easy to create a strong plain-text version without extra work.

Unsubscribe, consent, and compliance signals mailbox providers trust

One-click unsubscribe and visible sender identity

If people cannot easily leave, they will mark you as spam. That hurts deliverability far more than an unsubscribe ever will. Make the unsubscribe link obvious, keep the process fast, and avoid extra steps like forced logins.

One-click unsubscribe is especially important for Gmail and Yahoo ecosystems, where mailbox providers can show an unsubscribe action right in the inbox UI when your messages support it. Even if you are meeting the technical requirement behind the scenes, the user-facing rule is simple: make opting out painless.

Also make your sender identity consistent. Use a recognizable From name, a real reply-to address, and a footer that clearly states who you are and why the subscriber is receiving the email.

Permission-based signup and preference centers

High deliverability starts at signup. Use permission-based forms, clear language about what subscribers will receive, and avoid pre-checked consent boxes. If you collect email addresses offline or through partners, document the consent flow and be conservative with how you mail those contacts.

A preference center can reduce unsubscribes and complaints by letting subscribers choose frequency or topics instead of fully opting out. Even a simple setup helps:

• “Weekly digest” vs “product updates”
• Topic checkboxes (new releases, tips, events)
• A “pause for 30 days” option for seasonal audiences

This keeps engagement higher because subscribers stay in control.

Monitor and minimize spam complaints

Spam complaints are one of the fastest ways to damage sender reputation. Watch complaint rate by campaign and by source. If a specific signup path, lead magnet, or segment produces more complaints, fix that root cause rather than “sending harder.”

To reduce complaints, focus on three levers: set expectations at signup, send to engaged segments first, and keep content aligned with what subscribers thought they were joining. In Mailscribe, combine list hygiene with engagement segmentation so you are not repeatedly emailing people who have stopped wanting your messages.

How to spot deliverability issues using bounce codes and inbox tests

Track delivery, bounce, and complaint metrics

Deliverability problems usually show up in your metrics before you see a dramatic revenue drop. Track these at both the account level and per campaign:

• Delivered rate (sent minus bounces): a sudden dip often points to list quality, throttling, or blocks.
• Hard bounces vs soft bounces: hard bounces are permanent and should be suppressed. Soft bounces can be temporary (mailbox full, rate limited), but repeated soft bounces can still signal trouble.
• Spam complaint rate: spikes often come from a specific segment, signup source, or an email that surprised people.
• Opens and clicks (directionally): a sharp drop, especially on your most engaged segment, can be an inbox placement warning.

When you review bounce logs in Mailscribe, look for patterns by domain (Gmail vs Outlook) and by message. The “why” matters more than the raw count.

Use seed tests across major inbox providers

Inbox placement is not the same as delivery. A message can be “delivered” and still land in spam, promotions, or a tab that underperforms for your audience.

Use seed tests by sending the same campaign to a small set of real addresses across major providers (Gmail, Outlook, Yahoo, iCloud) before your full send. Check three things: inbox vs spam placement, whether images and links load cleanly, and whether the From name and subject look trustworthy on mobile.

Seed tests are especially useful after any change to authentication, templates, or sending volume.

Watch blocklists and authentication failures

If you see unexplained delivery drops, check for authentication failures first: SPF pass/fail, DKIM pass/fail, and DMARC alignment. A single misconfigured sending source can quietly break alignment and cause placement issues.

Also monitor reputable blocklists if your audience includes corporate inboxes. If you appear on a blocklist, treat it as a symptom. The fix is usually improving list hygiene, reducing complaints, and confirming every sender is properly authenticated, not just requesting removal and moving on.