How to troubleshoot soft bounces with 554 SMTP code in Salesforce Marketing Cloud?
Michael Ko
Co-founder & CEO, Suped
Published 6 Jul 2025
Updated 19 Aug 2025
6 min read
Encountering a high volume of soft bounces, especially those with the 554 SMTP code, can be incredibly frustrating. It often feels like you are hitting a brick wall, watching your email deliverability rates plummet without a clear understanding of why. In Salesforce Marketing Cloud, a 554 soft bounce indicates a transient problem, but in reality, it often points to deeper issues that require immediate attention.
I've seen many marketers struggle when their deliverability is suddenly affected across different domains, particularly when a significant portion of their audience is on platforms like Outlook. The initial thought might be to segment your list and re-engage the bouncing addresses later, but this approach alone may not resolve the underlying issue causing the 554 errors.
The key to resolving these soft bounces lies in understanding the specific bounce messages and the context behind them. Salesforce Marketing Cloud (SFMC) provides mechanisms to retrieve this critical information, which is essential for diagnosing and fixing the problem. Let's delve into how to effectively troubleshoot these challenging 554 SMTP codes.
Understanding 554 SMTP soft bounces
SMTP (Simple Mail Transfer Protocol) codes are a standard way for email servers to communicate the status of an email delivery. A 5xx code generally signifies a permanent failure. However, a 554 SMTP code in Marketing Cloud can often be classified as a soft bounce, which might seem contradictory.
This occurs because SFMC, like other ESPs, has internal bounce management rules that might reclassify a typically hard bounce into a soft bounce if it believes there is a chance for future delivery after retries. The 554 code typically means "Transaction failed," indicating a generalized failure that isn't specific about the exact problem, unlike a 550 (mailbox not found). It suggests the transaction failed for unidentifiable reasons, but often points to recipient policy issues or content rejections.
Understanding 554 SMTP codes
A 554 SMTP code can be a generic response indicating a permanent failure, but it is often used by recipient mail servers to block messages due to policy violations, content issues, or perceived spam. Salesforce Marketing Cloud might categorize it as a soft bounce, meaning it will attempt to resend the email, even though the issue is likely persistent. This requires deeper investigation to uncover the true cause of the rejection.
These soft bounces are not always due to a full inbox or a temporary server glitch. Frequently, a 554 error signals that your email has been blocked or blacklisted by the recipient's mail server or an intermediary spam filter (such as Cisco Email Security Appliance). This can seriously impact your sender reputation if not addressed promptly.
Identifying the root cause in Marketing Cloud
To effectively troubleshoot 554 soft bounces in Salesforce Marketing Cloud, you need to dig into the details. The first step is to retrieve the complete SMTP bounce message. While SFMC classifies it as a soft bounce, the full message often contains clues from the recipient server or security solution regarding why the email was rejected.
Salesforce Marketing Cloud provides bounce data through System Data Views that you can query. This data includes the exact SMTP reply codes and the associated messages. This is crucial because a generic 554 code doesn't tell you much on its own, but the accompanying text often reveals whether it's a block from a specific domain like Yahoo or a third-party spam filter.
Retrieving bounce information
Accessing the full bounce message text is paramount. These messages can explicitly state if mail was blocked by a specific security solution or provide a URL for more details on the block. Without this information, troubleshooting becomes a guessing game. SFMC allows you to query this data directly.
Sample SQL query for 554 soft bounces in SFMCSQL
SELECT
jb.BounceEventType,
jb.SMTPBounceReason,
jb.SMTPBounceCode,
jb.IsSoftBounce,
jb.EventDate,
s.EmailAddress,
s.Domain
FROM
_JobBounces jb
JOIN
_Sent s ON jb.JobID = s.JobID
AND jb.ListID = s.ListID
AND jb.BatchID = s.BatchID
AND jb.SubscriberID = s.SubscriberID
WHERE
jb.SMTPBounceCode = '554'
AND jb.IsSoftBounce = 1
AND jb.EventDate >= DATEADD(day, -7, GETDATE());
You can use SQL queries in Automation Studio to pull bounce data from the _JobBounces data view, as outlined in our guide on how to get SMTP bounce messages. Pay close attention to the full text of the SMTPBounceReason field. This often provides the specific details from the receiving server, such as Microsoft Office 365 or Barracuda appliances, that indicates the actual reason for the block. This is the first thing you should check when dealing with a surge of 554 soft bounces.
Common reasons for 554 soft bounces
Once you have the full bounce messages, you can often pinpoint the exact reason your emails are being rejected. A 554 code, while generic, can be triggered by several factors related to your sending practices or recipient policies. Knowing these common causes will help you focus your troubleshooting efforts.
In B2B scenarios, where many subscribers use enterprise-level security solutions, 554 errors often signify that your IP address or sending domain has been put on a blocklist (or blacklist) by a corporate spam filter. These filters are highly sensitive to perceived spam or suspicious sending patterns. If you're seeing MITS_SMTP in your bounce messages, it indicates a Salesforce Marketing Cloud internal SMTP response, which means the external server didn't give a more specific error.
This usually means the external mail server simply terminated the connection without a detailed rejection code, often a sign that your emails are being actively rejected or throttled. This is a common tactic by receiving mail servers to handle what they consider problematic senders or content. It highlights the need to improve your sender reputation.
Common causes for 554 soft bounces
Initial troubleshooting steps
Sender reputation: Your IP or domain might be considered suspicious.
Check blocklists. Monitor your sender scores. Review recent sending behavior.
Content flagging: Spammy keywords, broken links, or suspicious formatting.
Run a deliverability test to check spam score. Review email content for red flags.
Authentication issues: Incorrect SPF, DKIM, or DMARC setup.
Recipient server policies: Strict filtering rules or temporary overload.
Examine if the issue is domain-specific. Contact the recipient's IT team if possible.
Strategies for resolution
Resolving 554 soft bounces requires a multi-faceted approach, focusing on improving your overall sender health and directly addressing any identified blockages. Simply re-engaging subscribers or retrying sends won't fix underlying reputation or content issues.
First, continuously monitor your bounce logs and analyze the detailed bounce messages. This feedback is invaluable for understanding specific rejections. Second, focus on list hygiene. Regularly clean your lists to remove inactive or problematic addresses to prevent future issues and maintain a high sending reputation. This is a critical step in improving deliverability and inbox placement.
Proactive strategies
Sender authentication: Ensure your SPF, DKIM, and DMARC records are correctly configured and aligned. A missing or misconfigured DKIM signature can lead to soft bounces.
Content quality: Avoid spam trigger words, excessive imagery, or broken links. Use plain text where appropriate.
List segmentation: Segment your audience based on engagement to send to your most active subscribers more frequently.
Reactive strategies
Analyze bounce messages: Get the full SMTP response from SFMC. Look for specific block messages or URLs.
Contact postmasters: If a specific blocklist or ISP is identified (e.g., Yahoo), reach out to their postmaster team to request delisting or provide more information.
Engagement monitoring: Implement a re-engagement strategy for less active subscribers before removing them.
Summary
The 554 SMTP soft bounce in Salesforce Marketing Cloud is a complex issue that demands a thorough investigation beyond its generic classification. By systematically analyzing full bounce messages, understanding potential causes, and implementing a comprehensive strategy for sender reputation and content, you can significantly improve your email deliverability.
Remember, proactive list management and maintaining strong sender authentication are crucial for preventing these issues. When a 554 error occurs, the solution often lies in the details provided by the receiving server. Focus on extracting and interpreting that information to get your campaigns back on track.
Views from the trenches
Best practices
Always retrieve the full SMTP bounce message text in Marketing Cloud, as the generic 554 code provides limited insight without it.
Regularly monitor your sender reputation and check if your IP or domain is on any blocklists (or blacklists).
Ensure SPF, DKIM, and DMARC records are correctly set up and aligned to prevent authentication-related rejections.
Segment your email lists based on engagement to maintain a healthy sending environment and reduce bounce rates.
Proactively clean your email lists by removing inactive or problematic subscribers to improve overall deliverability.
Common pitfalls
Relying solely on Salesforce Marketing Cloud's classification of 'soft bounce' for 554 errors without investigating the underlying cause.
Ignoring the specific bounce messages provided by recipient servers or security solutions, which contain crucial details for troubleshooting.
Assuming 554 bounces are always temporary and simply retrying sends without addressing reputation or content issues.
Failing to clean email lists regularly, leading to continuous bounces and damage to sender reputation.
Not monitoring deliverability to specific domains or ISPs, which can hide widespread blocking by corporate filters like Proofpoint or Barracuda.
Expert tips
Use SQL queries in Automation Studio to systematically pull and analyze detailed bounce data from SFMC's system data views.
When a 554 error is persistent, investigate if your emails are being blocked by specific security appliances or mail filtering services.
If a particular domain is heavily affected, try reaching out to their postmaster team with details from the bounce messages to understand their policies.
Consider adjusting your sending volume and frequency to specific domains if you notice a sudden surge in 554 bounces after a high-volume send.
Implement a comprehensive engagement strategy to keep your list active, as low engagement can contribute to reputation issues and increased bounces.
Marketer view
Marketer from Email Geeks says they were seeing a ton of soft bounces wrecking deliverability in one segment, with 99% being soft bounces, and was stumped on how to improve it, considering sending to inboxes and re-engaging soft bounces later.
2020-01-29 - Email Geeks
Marketer view
Marketer from Email Geeks says you can't calculate deliverability rate, but you can calculate delivery rate, and checking per-ISP stats and SMTP replies will provide valuable insights.
Cisco Email Security Appliance). This can seriously impact your sender reputation if not addressed promptly.
Yahoo or a third-party spam filter.
Microsoft Office 365 or 
Barracuda appliances, that indicates the actual reason for the block. This is the first thing you should check when dealing with a surge of 554 soft bounces.
Yahoo), reach out to their postmaster team to request delisting or provide more information.
