You've done everything right in Zoho, written a great email, set up the campaign properly, and hit send, only for it to land in someone's spam folder or never arrive at all. This is one of the most common frustrations we hear about, and it almost always comes down to email deliverability.

What is email deliverability?

Deliverability is simply the measure of whether your emails actually reach the inbox they were sent to, rather than being filtered into spam, blocked outright, or silently dropped. Sending an email is easy, getting it to land where it's supposed to is the harder part, and it depends on far more than just the content of the message itself.

Why it's such a hot topic

Every major email provider, Gmail, Outlook, and others, runs its own spam filtering system, and those systems are constantly being tightened to cut down on genuine spam. This means the bar for what counts as "trustworthy" email keeps rising, and something that worked perfectly well a year or two ago may no longer be enough on its own today.

What actually affects deliverability

• Authentication records like SPF, DKIM, and DMARC, which prove your emails genuinely come from where they claim to.
• Sender reputation, built up over time based on how recipients interact with your previous emails.
• Engagement, meaning whether people actually open, read, and reply to your emails, or ignore and delete them.
• List quality, since sending to old, invalid, or unengaged addresses damages your reputation more than it helps.
• Content and formatting, as certain patterns commonly associated with spam can still trigger filters even from a trusted sender.