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Bounce no more: how SMTP reduces email bounce rates

Dealing with email bounces is one of the top challenges marketers deal with in the quick-paced world of email marketing. These bounces happen when an email cannot be successfully sent to the inbox of the intended recipient for a variety of reasons. High bounce rates can diminish email campaign efficacy and harm sender reputation.

     But, SMTP is an under-appreciated hero who plays a critical part in reducing email bounces.

email bounce

This blog article will focus on the essential role that SMTP plays in lowering email bounce rates and how it helps email marketing campaigns thrive.


Understanding email bounces

Let's take a closer look at what email bounces are and why they matter before discussing the important role of SMTP in preventing them.

Email bounces occur when an email message cannot be successfully delivered to the recipient's inbox. These bounces fall into one of two categories:

  1. Soft Bounces: Temporary delivery errors are known as soft bounces. They frequently happen when the mailbox of the recipient is full, the service is momentarily down, or the message is too big to send. These problems usually get fixed with time, and a subsequent delivery attempt can result in the email being delivered correctly.
  2. Hard Bounces: Hard bounces are delivery failures that never recover. They happen when a recipient address is incorrect, a domain is unavailable, or a sender is blocked, which prevent emails from being delivered. Hard bounces show that the email will never be delivered to the intended recipient and that the mailing list should be deleted.


The success of email marketing initiatives can be impacted by both soft and hard bounces, which can have a detrimental effect on email deliverability and sender reputation.

bounce errors


Small guide for most common email bounce errors


Let's analyse some of the most popular email bounce issues in more detail, along with their potential causes:

1. Recipient Does Not Exist (Hard Bounce)

Error: This arises when the recipient's email address is incorrect or nonexistent.

Why It Happens: The email address may have been entered incorrectly by the receiver or it could have stopped being in use.

What to do: In order to avoid more hard bounces, remove the email address from your list. If there was a misspelling in the email address, maybe you have another way to ask the receiver to update it.

2. Mailbox Full (Soft Bounce)

Error: The recipient's mailbox has reached its storage limit and cannot accept any further messages.

Why It Happens: The inbox of the recipient may have gotten out of hand and become overloaded.

What to do: Hold and try the email delivery once more at a later time. If possible, advise the recipient to empty their mailbox so that new messages can be delivered.

3. Server Unavailable (Soft Bounce)

Error: The email server of the recipient is momentarily down.

Why It Happens: The recipient's email server may be experiencing maintenance, a server overload, or other technical difficulties.

What to do: Try sending the email again after some time, as this is frequently a temporary problem. Keep an eye out for the fix.

4. Blocked Sender (Hard Bounce)

Error: The email server of the receiver is blocking emails from your sender domain.

Why It Happens: The recipient's email server may have strong screening guidelines, or your sender domain may have a bad sender reputation.

What to do: Look into the reason behind the restriction and take action to enhance your sender reputation. If necessary, get in touch with your SMTP provider for more advice on the situation.

5. Invalid Domain (Hard Bounce)

Error: The recipient's email address's domain (for instance, does not exist.

Why It Happens: The recipient might have provided the wrong domain or the requested domain might not be active.

What to do: Delete the email from your contact list and check the legitimacy of the domain. Make sure the domains for upcoming entries are correct.


Mailtinni SMTP

How Mailtinni can help reducing email bounce rates



  1. πŸ”” Bounce Handling: Mailtinni instantly alerts the sender of any delivery problems with emails. This gives the sender the opportunity to take corrective action, such as eliminating incorrect email addresses from their list, fixing technical problems, or changing the content of their emails to conform with recipient server standards.

  2. β˜‘οΈ Validation and Verification: Before attempting delivery, Mailtinni can check recipient addresses in real-time. This includes ensuring that the recipient's server can be contacted, that the recipient's inbox exists, and that there are no invalid domains. Our system aids in avoiding harsh bounces by alerting of incorrect or nonexistent addresses.

  3. πŸͺͺ Authentication: SPF (Sender Policy Framework) and DKIM (DomainKeys Identified Mail) methods of authentication are made easier by Mailtinni. These measures lessen the possibility of emails being marked as spam or phishing attempts by assisting destination servers in confirming the legitimacy of the sender's domain.

  4. ⛔️ Spam Filtering: Inbuilt spam filters on SMTP servers scan incoming emails for questionable features. These filters can identify and hold emails that display spammy behaviour, lowering the possibility of sending emails that bounce.

  5. πŸ’― Reputation Management: Based on the sending behaviour, Mailtinni servers can keep track of a sender's IP reputation score. Still, you need to be on top and always keep an eye on your domain’s reputation. Avoiding blacklists and ensuring that emails are routed to the inbox rather than the spam folder require an excellent sender reputation.


reduce email bounce

Best practices for reducing email bounce rates


While the SMTP is essential for preventing email bounces, email marketers should also use the following recommended practises to further lower bounce rates:

  1. βœ… Regularly clean your email list: This means to periodically check the data and remove any email addresses that are incorrect or inactive. This minimises the chance of hard bounces brought on by invalid recipient addresses.

  2. 🀝 Use double Opt-In: To guarantee that subscribers have verified their email addresses, use a double opt-in process. This reduces the likelihood that your list may contain email addresses that are false or typed incorrectly.

  3. πŸ‘€ Monitor your sender reputation: Keep a close watch on your sender reputation score and take immediate action to resolve any issues. To establish a good reputation, have a regular sending schedule and engage with your audience.

  4. πŸ‘πŸΌ Comply with email regulations: Make that your email marketing campaigns abide by all applicable laws and regulations, including the CAN-SPAM Act in the US and the GDPR in Europe. Adopting these rules can reduce bounces brought on by non-compliance.

  5. πŸ’Œ Segment your email list: You should send customised emails to selected recipients by segmenting your email database. To increase engagement and decrease bounce rates, adjust your content to the areas of interest and preferences of each segment.


     β€ΌοΈ Deliverability and sender reputation can be compromised by email bounces, which can be harmful to the success of email marketing. Mailtinni can help you handle any mistakes, we make authentication easier, and real-time verification to help reduce email bounces.

     βœŒπŸΌ Email marketers may lower bounce rates, keep a good sender reputation, and make sure their emails get in the inboxes of their intended recipients by understanding the purpose of a great SMTP service and by putting best practises into practice.

     Say good-bye to email bounces forever by embracing the potential of Mailtinni ! πŸš€