Struggling with Email/SMS Deliverability Issues? If your emails land in spam folders or your SMS messages fail to reach recipients, you're not alone. Deliverability issues can significantly impact customer engagement, marketing performance, and business communication. In this guide, we will explore the causes of these issues and the best practices to improve Email/SMS Deliverability Issues in 2025.

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What Are Email/SMS Deliverability Issues?

Email/SMS Deliverability Issues occur when emails or text messages fail to reach the recipient’s inbox or phone due to various technical and compliance-related factors. These issues can significantly impact marketing campaigns, customer communication, and business engagement, leading to lower conversions and poor user experience.

Email Deliverability Issues

1. Emails Landing in Spam

One of the most common issues businesses face is their emails ending up in the spam folder instead of the recipient’s inbox. This happens due to:
✅ Lack of Authentication – Missing SPF, DKIM, and DMARC records can cause email providers to mark emails as spam.
✅ Poor Sender Reputation – Sending emails from blacklisted domains or using shared IPs with spammy senders can lower credibility.
✅ Spam Trigger Words – Excessive use of promotional words like “Free,” “Win,” “Urgent” can trigger spam filters.

2. High Bounce Rates

A high email bounce rate occurs when messages cannot be delivered to the recipient’s email address. This happens due to:
✅ Invalid or Fake Email Addresses – Sending emails to non-existent or inactive addresses results in hard bounces.
✅ Full Mailboxes – If a recipient's inbox is full, the email may bounce back as undeliverable.
✅ Temporary Server Issues – Soft bounces occur when the recipient’s email server is temporarily down.

3. Low Open Rates & Poor Engagement

If users are not opening emails, it negatively affects email reputation and future deliverability. Common reasons include:

✅ Irrelevant Subject Lines – Boring or misleading subject lines lead to low open rates.
✅ Poor Sending Times – Sending emails at the wrong time reduces engagement.
✅ Lack of Personalization – Generic emails fail to connect with users.

SMS Deliverability Issues

1. Carrier Filtering & Message Blocking

Mobile carriers filter messages that appear spammy or unverified. This results in non-delivery, especially for promotional messages. Reasons include:

✅ Using Unregistered Numbers – Businesses must use verified sender IDs or shortcodes for SMS campaigns.
✅ Overuse of Promotional Language – Carriers block messages with excessive use of discounts, free offers, or urgency.
✅ High Complaint Rates – If users frequently report SMS messages as spam, carriers may block the sender.

2. SMS Delivery Failures & Delays

Text messages may not be delivered or can be delayed due to:
✅ Poor Network Coverage – Recipients in areas with weak network signals may not receive messages instantly.
✅ International Restrictions – Some carriers block SMS from foreign numbers or unauthorized services.
✅ Do Not Disturb (DND) List – If recipients have enabled DND mode, promotional SMS may not be delivered.

3. High Opt-Out Rates

If users frequently unsubscribe from SMS marketing campaigns, it can indicate poor deliverability and engagement. Reasons include:

✅ Excessive Messaging – Sending too many SMS messages annoys recipients.
✅ Lack of Personalization – Generic messages make users feel disconnected.
✅ No Clear Value – If the SMS lacks useful information or offers, users may opt out.

How to Improve Email/SMS Deliverability?

✅ Authenticate Emails Properly – Set up SPF, DKIM, and DMARC to improve email security and trustworthiness.
✅ Use Verified SMS Sender IDs – Register shortcodes and sender names with telecom providers to reduce filtering.
✅ Clean Your Contact Lists – Remove invalid, inactive, or fake contacts regularly.
✅ Avoid Spam Triggers – Use a natural tone in emails/SMS and avoid excessive promotional words.
✅ Send at Optimal Times – Analyze audience behavior and schedule messages when they are most likely to engage.
✅ Provide Clear Opt-In/Opt-Out Options – Ensure users willingly subscribe and can easily unsubscribe to maintain compliance.

By following these best practices, businesses can improve Email/SMS Deliverability Issues and ensure messages reach the intended recipients without delays or spam filtering.

Common Causes of Email/SMS Deliverability Issues

Poor Sender Reputation

Using unverified email domains or sending bulk messages can reduce credibility.

SMS providers may flag messages from unknown numbers as spam.

Invalid or Inactive Contacts

Sending emails/SMS to outdated or fake addresses can increase bounce rates.

Regularly cleaning your email and SMS lists is essential.

Lack of Authentication

Not setting up SPF, DKIM, and DMARC for emails increases the risk of spam filtering.

SMS senders should register their numbers with carriers for better trustworthiness.

Excessive Use of Spam Triggers

Words like “FREE,” “WIN,” and “URGENT” can trigger spam filters.

Overusing capital letters and too many links in messages can lower deliverability.

High Complaint Rates

If users mark your emails or SMS as spam frequently, your sender reputation decreases.

Ensure that users willingly opt into receiving your messages.

How to Improve Email/SMS Deliverability

1. Authenticate Your Emails & SMS

• Implement SPF, DKIM, and DMARC to verify email authenticity.

• Use a dedicated IP address and register your SMS sender ID to increase trust.

2. Maintain a Clean Contact List

• Remove inactive and fake email addresses.

• Use double opt-in methods to ensure recipients genuinely want your messages.

3. Follow Best Messaging Practices

• Personalize emails/SMS messages to improve engagement.

• Avoid spam trigger words and maintain a professional tone.

• Use shortened but trusted URLs in SMS messages.

4. Monitor Deliverability Metrics

• Track open rates, bounce rates, and spam complaints.

• Use email/SMS analytics tools like Google Postmaster, Twilio, and SendGrid.

5. Test and Optimize Your Messages

• A/B test different subject lines, sender names, and message formats.

• Schedule messages at optimal times for better open rates.

Fixing Email/SMS Deliverability Issues requires continuous monitoring and strategic improvements. By authenticating your messages, maintaining a clean contact list, and optimizing content, you can increase message reach and engagement. Implement these best practices today to ensure your emails and SMS land exactly where they should—in your recipient’s inbox!