Deliverability and reputation

Deliverability is the discipline that explains why one email lands in the inbox and another, nearly identical, ends up in spam. It's not magic or luck: it's the result of three things you can control — your certified sender, your list quality, and your reputation — backed by arrobaMail's sending infrastructure. This guide explains how all of that works under the hood and, above all, how to read and protect your reputation.

It's a central topic, so we're going to take it slow and repeat the important ideas. If you've already seen something in essential concepts, here we go deeper.

What determines whether you reach the inbox

When you send a campaign, each recipient's mail server (Gmail, Outlook, Yahoo) makes a decision in milliseconds: inbox, spam, or rejection. To decide, it looks at three signals:

1. Is the sender who they claim to be? It confirms this with your domain's SPF and DKIM certification. Without that, it's suspicious from the start.
2. Does this domain have good reputation? In other words, is its sending history healthy — few spam complaints, few bounces, good open rates?
3. Does the list look legitimate? Sending to addresses that don't exist or that never asked to hear from you is a red flag.

arrobaMail works on all three: it helps you certify your sender, keeps your lists clean, and protects your reputation with its own sending engine. Let's look at that engine.

aMailMTA: the proprietary sending engine

aMailMTA is the sending engine built by TECSID, designed specifically to maximize deliverability across modern mail providers. It's what works behind the scenes every time you hit "send," and it does several things that protect your reputation without you having to think about them:

• Speed tailored to each provider. It doesn't send to Gmail at the same pace as Outlook. Each destination has its delivery rate fine-tuned to avoid looking like an aggressive mass send.
• Automatic throttling. If a provider starts rejecting emails, aMailMTA slows down on its own instead of pushing through. Pushing through is exactly what ruins reputation; slowing down in time protects it.
• IP warm-up. New sending addresses are "warmed up" gradually, with growing volume over time, so providers get to know them without raising alarms.
• Smart retries. If an email doesn't go through because of a temporary issue (a full inbox), it retries later. If the address doesn't exist (hard bounce), it doesn't push through: it flags it and moves on.

The underlying idea: sending well means sending with strategy, not in a rush. That strategy comes built in.

Reputation, in a single number: the Health Score

All that activity is summed up in an indicator you can check at a glance: the Health Score, a score from 0 to 100 that measures your account's reputational health. It's calculated from several combined factors — bounce rate, spam complaints, the quality of your imports, list hygiene, sender authentication, and your historical behavior, among others.

The Health Score isn't decoration: it's your reputation dashboard. It's worth checking often and, above all, reacting when it drops — before the problem grows. Each range has a clear reading:

• 80–100 · Healthy. You're in good shape. Keep up your current practices.
• 60–79 · Attention. Something changed. Review your recent sends and fix it before it gets worse.
• 40–59 · Medium risk. Pause large campaigns and clean up your lists before continuing.
• 0–39 · Critical. Stop non-essential sends and contact support to recover your reputation.

What to do if your Health Score drops

If you see the number fall or alerts pop up, don't panic: it almost always gets fixed by going back to the basics. In order:

1. Clean up hard bounces. Remove addresses that hard-bounced from your lists. Every send to a nonexistent inbox is a negative signal.
2. Pause non-critical campaigns until your reputation normalizes. It's better to wait a few days than to push through and sink further.
3. Review what changed in your recent sends. Did you import a new list (where did it come from)? Did you change senders? Did you suddenly increase frequency? The cause is almost always there.
4. If the problem is big, write to us. TECSID's support team can help you diagnose and recover.

Important: reputation is built over time and can be damaged quickly. A single mass send to a purchased or old list can undo months of good behavior. When in doubt, send less and better.

The four rules that keep you in the inbox

If you take away four ideas from this whole guide, make them these. We repeat them on purpose because they're the ones that move the needle the most:

1. Use your own domain and certify it. Never a free inbox (Gmail, Yahoo) as your sender. Verify SPF and DKIM — the step-by-step is in verify your sender.
2. Send only to those who gave permission. Consent is the foundation of everything. A purchased list hurts all of your legitimate sends.
3. Keep your base clean. Clean up bounces after every campaign and re-engage or remove inactive contacts periodically. A small, engaged list always beats a large, inactive one.
4. Watch your frequency. A steady, expected cadence builds reputation; spikes and long silences damage it.

Follow those four and your Health Score stays green almost on its own. To go deeper on the business side of all this, there's the deliverability page; and to understand why an email lands in spam, the article why your emails land in spam.