What does the "error dialing remote address" bounce code mean and is it controllable?
Michael Ko
Co-founder & CEO, Suped
Published 21 Apr 2025
Updated 10 Oct 2025
5 min read
Encountering an "error dialing remote address" bounce code can be frustrating, especially when you're trying to maintain optimal email deliverability. This specific message, often accompanied by i/o timeout, indicates a fundamental problem with the network connection between your sending mail server (or your Email Service Provider's) and the recipient's mail server.
Unlike bounces caused by invalid recipient addresses or content issues, this error points to a failure to even establish communication at the TCP level. It's like trying to call someone, and the phone doesn't even ring, let alone get an engaged tone.
This guide will demystify this bounce code, explore its common causes, and outline the extent to which you can control or mitigate its impact on your email campaigns.
Decoding the "error dialing remote address" bounce
The full error message "error dialing remote address: dial tcp [sender_ip]:port->[recipient_ip]:25: i/o timeout" explicitly states that the SMTP client failed to establish a TCP connection with the remote mail server. The dial tcp part refers to the attempt to initiate this network connection, and the i/o timeout means the attempt exceeded the allowed time limit without a successful handshake.
Error dialing remote address: The overall issue is a failure to connect to the recipient's mail server.
Dial tcp: The process of initiating a Transmission Control Protocol connection.
IP addresses and port 25: Shows the attempted connection from your server's IP to the recipient's server IP on the standard SMTP port 25.
I/O timeout: The connection attempt exceeded the allowed time limit without a response from the remote server.
This type of bounce is generally considered a soft bounce. It's a temporary failure, meaning the sending server might retry delivery later. If subsequent attempts also fail, it can escalate to a permanent (hard) bounce. Understanding email bounce codes is crucial for effective email management.
It's important to distinguish this from other common SMTP bounce codes that indicate issues like a full mailbox or a nonexistent recipient. Here, the issue is purely with the initial network handshaking, not the content or recipient validity.
Primary causes of this connection timeout
The most common culprit behind an "error dialing remote address" bounce is a problem on the recipient's mail server. This could include the server being temporarily overloaded, experiencing downtime, or having misconfigured network settings that prevent it from accepting new connections.
Network congestion or routing problems between your sending infrastructure and the recipient's server can also trigger these timeouts. Sometimes, a firewall or security measure on the recipient's end might be aggressively blocking connections, leading to a timeout rather than an explicit rejection.
While less direct, your sending IP address (or that of your ESP) might be on a DNS-based Blackhole List (DNSBL) or another blocklist. If this occurs, some recipient servers might silently drop connection attempts, leading to a timeout. Regular blocklist monitoring is a wise preventative measure.
Sender's control and influence over this error
It is important to acknowledge that direct control over error dialing remote address bounces is often limited for the sender. The issue fundamentally lies with the remote server's availability or the network path leading to it, which are typically outside your immediate influence.
Sender's indirect influence
While you can't fix their server, maintaining a stellar domain reputation ensures your emails are generally welcomed. Poor reputation can lead to more aggressive filtering, potentially including connection drops or throttling that result in timeouts.
Reputation: High reputation helps ensure your connections aren't prematurely terminated by spam filters, sometimes causing timeouts.
Email authentication: Implementing DMARC, SPF, and DKIM reduces the likelihood of your emails being treated suspiciously.
Remote server control
The primary control resides with the recipient's mail server administrators. Their server's health, network configuration, and security policies dictate whether it accepts incoming TCP connections promptly. You cannot directly influence these factors.
Server uptime: The recipient server might be down or experiencing heavy load, leading to unresponsiveness.
Firewall configuration: Improper firewall rules on the recipient's side can silently drop connection requests.
Network routing: Issues with internet routing infrastructure can prevent the connection from reaching the destination.
If you're using a reputable Email Service Provider (ESP), they are typically equipped to handle these transient errors. They will usually retry sending the email over a period, giving the remote server time to recover or for network issues to resolve. This process is crucial for recovering from such deferrals.
Practical steps to improve deliverability and reduce these bounces
While you can't directly control the remote server, several proactive measures can significantly improve your overall email deliverability and minimize the occurrence of connection-related bounces.
Strengthen email authentication: Ensure your SPF, DKIM, and DMARC policies are correctly set up and enforced. This builds trust with recipient servers.
Monitor your sender reputation: Regularly check your sending IP and domain reputation. Getting on a blacklist (or blocklist) can lead to servers refusing connections outright, or silently dropping them.
Maintain clean mailing lists:Remove inactive or invalid email addresses regularly. A high bounce rate, even soft bounces, can negatively impact your sender score.
Use a reliable ESP: A good Email Service Provider will have robust infrastructure and sophisticated retry mechanisms to handle transient network issues, minimizing the impact of these bounces.
DMARC reporting is particularly useful here. A DMARC monitoring tool like Suped can provide insights into delivery issues, helping you spot trends or persistent problems that might contribute to error dialing remote address bounces, even if the primary cause is external.
Views from the trenches
Best practices
Ensure your sending infrastructure is robust and your ESP has strong retry logic for transient errors.
Consistently monitor your IP and domain reputation to avoid being unexpectedly throttled or blocked.
Regularly audit your DNS records, especially SPF and MX, to prevent configuration issues on your side.
Maintain a clean mailing list to reduce overall bounce rates and signal good sending practices.
Implement DMARC at an enforced policy (p=quarantine or p=reject) to protect your domain's authenticity.
Common pitfalls
Overlooking infrastructure issues on the recipient's side, assuming the problem is always yours.
Ignoring soft bounces, as a high volume can still negatively impact sender reputation over time.
Failing to implement proper email authentication, which can make your legitimate emails look suspicious.
Not using a dedicated DMARC monitoring solution to gain visibility into delivery issues and authentication failures.
Sending to unengaged or old lists, increasing the likelihood of hitting inactive mailboxes or spam traps.
Expert tips
Look for patterns in these bounces, such as specific recipient domains or geographic regions, to identify broader issues.
Collaborate with your ESP to understand their retry logic and how they handle persistent soft bounces.
Consider contacting the recipient's postmaster if you see widespread, persistent
"error dialing remote address" errors for their domain.
Understand that sometimes, these errors are entirely out of your hands, stemming from external network instability.
Expert view
Expert from Email Geeks says that this bounce code points to a TCP connection timeout, not a DNS resolution problem, which is a key distinction for troubleshooting.
2023-01-15 - Email Geeks
Marketer view
Marketer from Email Geeks says that this error is often part of a deferral process that can ultimately lead to the message being denied delivery if the issue persists.
2023-02-20 - Email Geeks
Minimizing the impact of connection errors
While an "error dialing remote address" bounce code may seem cryptic and outside your immediate influence, understanding its root causes empowers you to take proactive steps. By focusing on robust email authentication, maintaining a strong sender reputation, and utilizing dependable sending infrastructure, you can significantly mitigate the frequency and impact of these transient connection failures.
DMARC, 
SPF, and 
DKIM reduces the likelihood of your emails being treated suspiciously.
