Question 1

What is the difference between a hard bounce and a soft bounce?

Accepted Answer

A hard bounce occurs when an email is permanently undeliverable—typically because the email address doesn't exist, the domain is invalid, or the recipient server has blocked delivery. A soft bounce is a temporary delivery failure, often caused by a full inbox, server downtime, or message size limits. Hard bounces should be removed immediately, while soft bounces may resolve on their own.

Question 2

How often should I clean my email list?

Accepted Answer

We recommend cleaning your email list at least once per quarter, or before any major email campaign. For high-volume senders, monthly cleaning is ideal. Email addresses decay at a rate of about 22% per year due to job changes, domain expirations, and abandoned accounts. Regular verification prevents bounce rates from creeping up and protects your deliverability.

Question 3

What is a catch-all email domain?

Accepted Answer

A catch-all (or accept-all) domain is configured to accept emails sent to any address at that domain, regardless of whether the specific mailbox exists. For example, if company.com is a catch-all, both real@company.com and fake123@company.com would be accepted. This makes it impossible to verify if a specific mailbox exists, so these are typically flagged as "risky."

Question 4

Is email verification GDPR compliant?

Accepted Answer

Email verification can be GDPR compliant when done correctly. The key is that verification services should process email addresses solely for verification purposes, not store data longer than necessary, and not share data with third parties. The verification process typically doesn't send actual emails, so there's no unsolicited contact with data subjects.

Question 5

What is sender reputation and why does it matter?

Accepted Answer

Sender reputation is a score that Internet Service Providers (ISPs) assign to your sending domain and IP address based on your email sending behavior. Factors include bounce rates, spam complaints, engagement rates, and sending volume consistency. A poor sender reputation can cause your emails to land in spam folders or be blocked entirely, even for legitimate recipients.

Question 6

What is SPF and how does it work?

Accepted Answer

SPF (Sender Policy Framework) is an email authentication protocol that allows domain owners to specify which mail servers are authorized to send emails on their behalf. When an email is received, the recipient server checks the SPF record in DNS to verify the sending server is authorized. This helps prevent email spoofing and improves deliverability.

Question 7

What is DKIM and why is it important?

Accepted Answer

DKIM (DomainKeys Identified Mail) is an email authentication method that adds a digital signature to outgoing emails. This signature is verified by the recipient's server using a public key published in your DNS records. DKIM proves that the email content hasn't been tampered with during transit and confirms the sender's identity.

Question 8

What is DMARC and how does it protect my domain?

Accepted Answer

DMARC (Domain-based Message Authentication, Reporting & Conformance) is a policy that tells receiving servers what to do when emails fail SPF or DKIM checks. You can set policies to monitor, quarantine, or reject failing emails. DMARC also provides reports on who is sending email using your domain, helping you identify unauthorized senders.

Question 9

What is a spam trap and how can it hurt my deliverability?

Accepted Answer

Spam traps are email addresses used by ISPs and anti-spam organizations to identify senders with poor list hygiene. There are two types: pristine traps (never used by real people) and recycled traps (abandoned addresses repurposed as traps). Sending to spam traps signals that you're not maintaining your list properly and can severely damage your sender reputation.

Question 10

What is a disposable or temporary email address?

Accepted Answer

Disposable email addresses are temporary inboxes created for one-time use, often to avoid spam or bypass registration requirements. Services like Guerrilla Mail, 10 Minute Mail, and Mailinator provide these addresses. They're problematic for businesses because they indicate low-quality leads who don't want ongoing communication.

Question 11

What is a role-based email address?

Accepted Answer

Role-based email addresses are generic addresses tied to a function rather than a person, such as info@, support@, sales@, or admin@. These addresses often have multiple recipients or are monitored by different people over time. They typically have lower engagement rates and higher complaint rates, making them risky for marketing campaigns.

Question 12

What is an acceptable bounce rate for email campaigns?

Accepted Answer

Industry best practice is to maintain a bounce rate below 2%. Rates above 5% can trigger spam filters and damage your sender reputation. Hard bounces should be kept under 0.5%. If you're seeing higher rates, it's a sign that your list needs cleaning or your acquisition methods need improvement.

Question 13

How do MX records affect email deliverability?

Accepted Answer

MX (Mail Exchange) records are DNS entries that specify which mail servers accept email for a domain. When sending an email, your server looks up the recipient domain's MX records to find where to deliver the message. Invalid or missing MX records mean the domain cannot receive email, resulting in a hard bounce.

Question 14

What is email list decay and how fast does it happen?

Accepted Answer

Email list decay refers to the natural degradation of email list quality over time. On average, email lists decay at 22-30% per year. This happens because people change jobs, abandon email accounts, companies go out of business, and domains expire. Regular list cleaning is essential to combat decay and maintain deliverability.

Question 15

What is the difference between single and double opt-in?

Accepted Answer

Single opt-in adds subscribers immediately after they submit their email address. Double opt-in requires subscribers to click a confirmation link in a verification email before being added to your list. Double opt-in results in higher-quality lists with better engagement, fewer bounces, and reduced spam complaints, though it may result in fewer total subscribers.

Question 16

How do spam complaints affect my email deliverability?

Accepted Answer

Spam complaints occur when recipients mark your email as spam. ISPs track complaint rates, and high rates (above 0.1%) can severely damage your sender reputation. This can cause your emails to be filtered to spam folders or blocked entirely. To reduce complaints, only email people who opted in, make unsubscribing easy, and send relevant content.

Feature	WhylidateRecommended	Others
Accuracy	99.5% (AI-Powered)	~85% (Ping only)
Speed	Real-time	Batch delays
Pricing	Pay-as-you-go	Monthly subscriptions
Support	24/7 Live Chat	Email Tickets
API Rate Limits	Unlimited	Restricted
Disposable Detection
Catch-all Detection
GDPR Compliant		Varies

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