Why your outgoing email lands in spam

If you've noticed that your sent emails are landing in the spam or junk folder instead of recipients' inboxes, you're not alone. This issue is one of the most common challenges for online businesses and email marketing teams. But the good news is that "emails going to spam" almost always has clear and fixable causes. In this article, in simple language with practical examples, we'll examine four main factors: sender authentication, IP reputation, message content, and blacklists. At the end, we'll provide you with a practical checklist for testing and resolving the issue.

1. Sender Authentication: Why Are SPF, DKIM, and DMARC Critical?

Email services like Gmail and Yahoo first check whether the email was actually sent by you before delivering it. This verification is done using three main protocols: SPF, DKIM, and DMARC. If any of these are not properly configured, the likelihood of your email going to spam increases significantly.

SPF (Sender Policy Framework)

SPF specifies which servers are authorized to send emails for your domain. This is done with a TXT record in DNS. Example:

example.com.  IN  TXT  "v=spf1 include:_spf.google.com ~all"

In this example, only Google servers are authorized to send, and the rest are marked as "softfail" with the ~all flag. Common mistake: using +all, which allows any server to send and effectively renders SPF useless.

DKIM (DomainKeys Identified Mail)

DKIM adds a digital signature to your email, created by the sending server's private key. The recipient verifies it using the public key available in DNS. To activate it, you need to add a record like the following to your DNS:

default._domainkey.example.com.  IN  TXT  "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQC..."

Important note: If you're using a specific email service provider (like cPanel or Zoho), they usually provide the DKIM key ready-made. You just need to copy it.

DMARC (Domain-based Message Authentication, Reporting & Conformance)

DMARC tells the recipient what to do if SPF or DKIM fails. A DMARC record typically looks like this:

_dmarc.example.com.  IN  TXT  "v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com"

The value p=quarantine means invalid emails go to spam. If p=none, you only receive reports and no action is taken. Common mistake: setting DMARC to p=reject before ensuring SPF and DKIM are correct, which can cause your legitimate emails to be rejected as well.

2. IP Reputation: Why Does Your IP Matter?

Even if sender authentication is complete, if your IP has a bad reputation, your emails will go to spam. IP reputation is built based on factors such as complaint rate, open rate, and sending volume.

Shared vs. Dedicated IP

If you're using shared hosting, your IP is shared with dozens or hundreds of other users. If one of them sends spam, your IP reputation gets damaged too. Solution: For high-volume email sending (e.g., more than 5,000 emails per month), definitely use a dedicated IP. Services like ServerNet provide the option to obtain a dedicated IP for email servers, which can help improve deliverability.

IP Warming

If you have a new IP, you shouldn't send a large volume of emails all at once. Instead, gradually increase the volume:

• Week 1: 500 emails per day
• Week 2: 1,000 emails per day
• Week 3: 2,000 emails per day
• Week 4: Reach your main volume

This gives email services confidence that you are a legitimate sender.

Checking IP Reputation

To check your IP reputation, you can use services like Sender Score (site sender.score) or Talos Intelligence. A score above 80 out of 100 is usually good. If the score is low, you need to find the cause: Is the complaint rate high? Are your emails being sent to invalid addresses?

3. Message Content: What Makes You Look Like Spam?

Modern spam filters don't just look at keywords; they also examine behavioral and structural patterns. However, some classic issues are still important.

High-Risk Words and Phrases

Using words like "free," "special discount," "limited opportunity," "click here," and "money" can trigger spam algorithms. But the important point is that these words alone aren't problematic; combining them with other factors (like low open rates) increases the risk.

Text-to-Image Ratio

If your email is mostly images with little text, spam filters will find it suspicious. Simple rule: at least 60% text and at most 40% images. Also, be sure to write alt text for images.

Suspicious Links

If you use shortened links (like bit.ly) or links pointing to unknown domains, the likelihood of being marked as spam increases. It's better to use your own domain and display links with clear text.

4. Blacklists: Is Your IP or Domain Blocked?

If your IP or domain is on one of the well-known blacklists, your emails will automatically go to spam or even be rejected. Well-known blacklists include: Spamhaus, Barracuda, SpamCop, and SORBS.

How to Check?

Open the MXToolbox tool and enter your IP or domain in the Blacklist Check section. If you're on a blacklist, it usually shows the reason and the removal process.

Why Do We End Up on a Blacklist?

• Sending emails to purchased or scraped addresses
• High user complaint rate (above 0.1%)
• Lack of an unsubscribe link in the email
• Sending a large volume in a short period without IP warming

Process of Removal from a Blacklist

After fixing the main issue (e.g., removing invalid addresses from your list), you need to submit a removal request. Each blacklist has its own form. It usually takes between 24 hours and a few days. During this period, reduce email sending and only send to active users.

Final Checklist: 7 Steps to Fix the Email-to-Spam Issue

1. Check and fix SPF, DKIM, and DMARC records. Use online tools for testing.
2. Check your IP reputation. If the score is below 80, find the cause.
3. Use a dedicated IP if your sending volume is high.
4. Check blacklists and submit a removal request if needed.
5. Optimize email content: more text, fewer images, valid links.
6. Clean your contact list: remove invalid and inactive addresses.
7. Send a test email to Gmail, Yahoo, and Outlook addresses and see which one goes to spam.

In the end, remember that solving the "email to spam" issue is a gradual process. Even after fixing all the problems, it may take a few weeks for your reputation to be fully rebuilt. Be patient and regularly review delivery reports. If you're looking for a reliable infrastructure for sending emails, ServerNet's email hosting services can be a good option to start with, but the most important thing is to properly implement the principles we discussed in this article.