Once you hit the send button, every email should safely land in the recipient’s inbox. But unfortunately, we don’t live in a perfect world.
Up in the cloud, your emails might bounce, fail, or block.
Thankfully, that’s where SMTP errors come into the picture to shed some light on otherwise invisible chatter.
In this article, we will take up the SMTP error codes and see how to avoid these for smoother email delivery.
SMTP is a Simple Mail Transfer Protocol that is responsible for sending emails.
But how will the sender know whether it has reached its destination? That’s done with a specific response code that the SMTP server sends to the mail client. In case there are any issues with the message delivery, an SMTP error code is sent to notify the sender.
There are broadly following categories of SMTP codes.
Absolutely no. SMTP codes are shared to confirm the delivery status and don’t necessarily relay an error.
For example- The SMTP code starting with 2, like 250, denotes a successful email delivery.
However, any user notices the codes usually when it reports an issue.
SMTP 400 Error Codes
These codes denote a temporary error code that you can try to resolve by resending the email.
SMTP 500 Error Codes
It denotes a permanent email failure and details the cause of the issue.
SMTP 200 Codes
Other SMTP Codes
1. Understand the Issue
Start with deciphering the error code sent by the server. The error is usually accompanied by the possible action points you can take to resolve it. So, it’s critical to pay enough attention to the concern.
Start by gathering basic information to get started.
2. Locating the Authoritative Name Servers
Nameserver is a library with all the DNS records. If your DNS records have changed in the last 24 hours, check with the nameserver’s owner whether the new information is updated.
You can run the whois command to find the nameserver’s owner.
3. Test the Server With Telnet
You can use the telnet command to verify the domain information. Using the telnet command, you can log into the server through port 25, which is the default SMTP port).
If you get a 220 response, you are good to start with your emails.
4. Use Webmail
You can use webmail to verify if your connection is in working condition or needs additional configuration.
After logging in to webmail, you can send a test email to a secondary email address that works fine.
The outbound mail server works as expected if the email is sent and received successfully.
Now, reply to the email from the secondary email address. The inbound email server also works if you receive the email in the webmail interface. It confirms that the issue is not on your server.
If for some reason, the email delivery fails, the next step is to check the email log entries for error codes.
Who knew sending a simple email could have such technicalities at the backend?
But the good news is that nothing can intimidate you if you got the basics covered. If you can really read the error codes, it will give away the solutions on its own.
But since email deliverability is a critical aspect of any marketer’s email game, one might not have the luxury of time to learn through trial and error.
In that case, fast-tracking with a reliable SMTP relay service provider can change your delivery rate for good. Whether you are sending ten or ten thousand emails, SendPost can be the perfect match for you. It supports 14+ programming APIs for flexible integration. With over 99% average delivery rate, you can amplify your outreach and conversions.