The reality of email marketing shows worrying data: 21% of legitimate emails end up classified as spam. The messages that fall into this folder barely reach 1.5% of reads, while emails in the main folder achieve a 14.5% open rate.

Today’s spam filters use advanced systems to detect specific terms and expressions. Every time your emails are marked as spam, your sender reputation suffers a negative impact that can affect your future communications.

You will discover in this guide the critical words to avoid in your emails, techniques to create subject lines that generate opens and proven methods to ensure that your messages reach your recipients’ inboxes. The goal is to significantly improve your delivery rates and maintain effective communication with your audience.

Reasons why your emails end up in spam

Email filtering systems have evolved to protect users. We explain how these filters work and what you should do to prevent your emails from being marked as spam.

Operation of automatic filters

Email providers use intelligent filters that evaluate each message using advanced algorithms. When you send an email, the system analyzes multiple elements:

• Authenticity of your sending domain
• Message content
• Shipping patterns
• History of previous interactions

Words that trigger alerts

Terms related to money, offers or urgency immediately trigger spam filters. Excessive use of capital letters, exclamation points or currency symbols can also mark your message as spam.

Remember that words such as “free”, “offer”, “urgent” or “special promotion” are considered suspicious by filters. The combination of these words considerably increases the risk of your message being filtered.

Your reputation as a sender

Did you know that your sender reputation is measured on a scale of 0 to 100? A higher score means better delivery of your mailings. This reputation depends on two main factors:

• Your IP reputation
• The reputation of the sending domain

The following items can damage your reputation:

• High bounce rates in your campaigns
• Frequent spam complaints
• Little interaction with your emails
• Irregular mass mailings

The sender’s reputation determines whether your messages will reach the main inbox or be filtered as spam. We recommend you to maintain a constant and quality communication with your subscribers to protect your reputation.

Critical words to avoid in your business

We explain which words can affect the deliverability of your emails. Our experience of more than 12 years in email marketing allows us to identify the terms that trigger spam filters.

Money and benefits terms

Spam filters immediately detect words related to financial benefits. We recommend avoiding terms such as “easy money”, “additional income” or “real profit”, as they trigger automatic alerts. The use of currency symbols ($, €) or percentages also increases the risk of your email being flagged as spam.

Expressions of urgency

Did you know that phrases that generate temporary pressure can permanently damage your sender reputation? Words like “do it now”, “urgent” or “for a limited time” not only trigger filters, but also cause your subscribers to block your emails.

Promotional terms

Our email verification service has detected that overly promotional words represent the highest risk for deliverability. Terms such as “free”, “free access” or “special promotion” are constantly monitored by anti-spam filters. However, a legitimate promotion can work if you communicate it professionally.

To improve your delivery rates, we suggest these alternatives:

• Use “specific availability” instead of “limited supply”.
• Prefer “develop opportunities” over “make money”.
• Choose “know more details” rather than “act now”.

Spam filters are constantly evolving to protect users. Therefore, keep your language professional and avoid terms that seem manipulative. Remember that a clear and direct subject line will always have better results than one full of exaggerated promises.

Techniques for creating issues that generate openings

Want to double your open rates? Well-crafted subject lines make the difference between the success and failure of your campaigns. Our studies show that an effective subject line can significantly multiply your open rates.

Structure that works

The perfect length of your subject line is like an old tweet: less is more. We recommend keeping your subject lines under 50 characters to ensure full display. Remember that each email manager has its limits:

• Gmail: 70 characters
• Hotmail: 60 characters
• Yahoo: 46 characters

To maximize the impact of your subject lines, place keywords at the beginning. Data shows that personalization can increase your openings by up to 29%.

A/B testing is your best ally in perfecting your business. Experiment with different versions until you find the one that best connects with your audience.

The right tone for your audience

The tone of your message should be like a tailored suit: perfectly adapted to the recipient. Baby Boomers prefer formal and direct communication, while Millennials respond better to authentic and conversational messages.

Adapt your language according to the sector:

• Technical sector: Accurate and detailed as a manual
• Creative field: Informal as a chat among colleagues
• Small business: Personal as a coffee with friends
• Corporate Client: Formal as a business meeting

Don’t forget that excessive capitalization and exclamation points are like shouting in a library: they attract negative attention and trigger spam filters.

Personalizing the sender can increase your opens up to 28%. For example, “Ana de [Empresa]” generates more trust than a simple corporate name.

The success of your issues requires constant monitoring. Interaction metrics and feedback from your subscribers will guide you to adjust your tone and language. As we say in Verificaremails: “The best strategy is the one that adapts to your audience”.

Essential tools to improve email deliverability

Did you know that the right tools can double the effectiveness of your campaigns? We explain the solutions you need to ensure that your emails reach their destination.

Email Verifier

The email verifier we use offers 99% accuracy in address validation. Our experience has allowed us to develop a system that detects and eliminates:

• Typographical errors in mailings
• Hidden spam traps
• Generic accounts that damage your reputation

We recommend using DKIM, SPF and DMARC protocols to protect your mailings against phishing and malicious practices.

Telephone validation system

Being able to validate phone number of numbers is essential to keep your database clean. Our system automatically verifies each number added through your forms.

The process includes:

• Numerical format validation
• Country code verification
• Real-time verification

If a number does not include a country code, don’t worry – our system performs an intelligent validation based on location.

APIs to automate verification

The validation API we offer performs more than 25 simultaneous checks, including grammar, spelling and vendor validation, all in less than 500ms.

Our api for mobile verification allows you to:

• Automatically validate numbers
• Detect invalid numbers instantly
• Reduce costs in your SMS campaigns

Remember that these tools not only improve delivery – they protect your reputation as a sender. If you have any doubts about which solution is best for you, our support team will be happy to help you choose the most suitable option.

Proven practices to keep your emails out of spam

Do you want to ensure that your emails always arrive in the main inbox? We explain the three fundamental keys: updated lists, personalized content and accurate metrics.

Keep your lists clean

Database contacts expire. For databases with more than 1 million emails, it is recommended to validate them every 2 weeks, while for smaller databases, validating them once a quarter is sufficient.

Our verification service helps you to identify and eliminate:

• Invalid or error messages
• Inactive contacts (6-12 months without interaction)
• Terminations and cancellations
• Directions that generate bounces

Remember that legitimate emails can become spam traps after 6 months of non-use. A clean list improves your reputation and increases the successful delivery of your campaigns.

Customize your content

Effective personalization generates measurable results: 27% more unique clicks and 11% more opens than generic messages. We recommend:

• Adapt content according to previous interactions
• Segment by behavior
• Adjust the pitch for each group
• Create preference-based content

An email checker maintains the quality of your data, while the phone checker service ensures accurate contact information.

Monitor your metrics

Our years of experience have enabled us to identify critical indicators:

• Delivery: Over 95%
• Rebounds: Maximum 2%.
• Spam complaints: Less than 0.1%.
• Openings: Between 15% and 25%.

To optimize these results, use our email validation API for real-time verification. The phone verification api complements the contact validation.

Deliverability works like a cycle: the right content, to the right contacts, at the right time. It tracks both positive interactions (clicks, opens) and negative interactions (complaints, unsubscribes).

A/B testing is essential for continuous improvement. If you have questions about how to implement these practices, our support team is available to help you.

Conclusion

Want to keep your emails out of spam? Our 12 years of experience in email marketing have taught us that success requires a precise combination of strategies. Careful word selection, regular list maintenance and specialized tools are the cornerstones of your campaigns.

Your reputation as a sender is like a credit card: every action adds or subtracts points. Our email address verification service is 98% accurate, Verificar Emails uses industry best practices and hundreds of customers are proof of that. It is not originally designed to find the verified email address of any professional, but some people use it in such this way. We recommend that you maintain a professional tone and avoid problematic terms that could damage your credibility.

Spam filters are constantly evolving, but by following the guidelines in this guide, you will multiply your chances of making it to the main inbox. Remember that email validation improves the quality of your databases and in real time ensures the veracity of emails captured in forms and applications of all kinds.

If you have questions about how to implement these recommendations, our support team will be happy to help you develop an effective strategy for your specific needs.

FAQs

Q1. What words should I avoid in my e-mails so that they are not marked as spam?
It is advisable to avoid terms related to money (such as “easy money” or “additional income”), phrases of urgency (“do it now”, “urgent”) and overly promotional expressions (“free”, “limited offer”). It is also important not to use excessive capitalization, exclamation points or monetary symbols.

Q2. How can I improve the deliverability of my emails?
To improve deliverability, use tools such as email verifiers to validate addresses, keep your contact lists updated, personalize content for your audience and constantly monitor delivery metrics such as open and bounce rates.

Q3. How long should the subject line of my e-mails be?
It is recommended to keep subjects under 50 characters to ensure full display in most inboxes. Put the most important words at the beginning and consider that different mail managers display different amounts of characters.

Q4. How can I personalize my e-mails effectively?
Effective personalization goes beyond including the recipient’s name. Tailor content based on interaction history, segment your audience based on previous behavior, use an appropriate tone for each group, and create relevant content based on your subscribers’ demonstrated preferences.

Q5. What metrics should I monitor to ensure good deliverability of my mailings?
Key metrics include deliverability rate (should be above 95%), bounce rate (should not exceed 2%), spam complaints (keep below 0.1%) and open rate (between 15% and 25% is considered healthy). Monitoring these metrics will help you adjust your email marketing strategy.