Basically, this error message tells you that the email you sent was blocked by the recipient's email hosting server, and returned undelivered. It is an SMTP (Simple Mail Transfer Protocol) error code and can be written in several different ways. Usually, the phrasing of the error message depends on the hosting server sending the error. Here are some common ways they may be phrased:
SMTP Error 550
SMTP Error 5.5.0
550 Invalid recipient
550 User account is unavailable
550 – Requested actions not taken as the mailbox is unavailable.
550 Address rejected
550 No such user here
550 Not our Customer
550 Account not available
Remote host said: 550 – firstname.lastname@example.org, this yourdomain.com
Mailbox Does Not Exist – Giving up
240.240.240.240 does not like recipient
Remote host said: 550-Verification failed for email@example.com
550-Previous (cached) callout verification failure
550 Sender verify failed Giving up on xx2.xxx.xxx.xxx.
What are the causes of a 550 No Such User Error?
The error commonly occurs when the sending email is rejected because the destination email username cannot be found or is not accessible by the server. Here are the very likely causes of this error.
Your IP address is blocked by the recipient’s email hosting server.
Your email address has been compromised and has been blocked by recipient’s hosting server.
You are sending an email using an ISP that is different to the one you are currently logged on to.
The recipient’s email address cannot be found, or does not exist.
The recipient’s email has been suspended or temporarily disabled.
Your own domain name is invalid, cannot be found, or has been blocked.
Your email message is being treated as spoofed, and has been rejected by the recipient’s email hosting server.
The recipient’s email hosting server tried to verify the sender email address, but was unable.
The recipient’s hosting server is down, and is unable to receive the email.
The recipient’s inbox is full, and is unable to receive the email.
The recipient’s email hosting has an anti-spam firewall, and has labelled your message as spam.
Your own Internet gateway has a firewall, or filtering feature, that intercepted your own email, regarded it as spam, and blocked it to stop you from accidentally sending out spam or a virus-infected email.
Your email account has been hacked, has been used to send out tons of spam mail, and so has been blocked by the recipient’s SPF (Sender Policy Framework).
Note: The SMTP 550 Error is often a problem at the recipient’s end, which means this error is usually caused by factors outside your email hosting server. However, there are some recommended steps you will want to take to see how you can address this error.
Troubleshooting to Fix a 550 No Such User Error
As noted earlier, this error is usually an error on the recipient’s end. But there may still be ways you can fix the problem. Here are some possible solutions:
Double-check the recipient’s email address. "550 No Such User Here" Errors can occur when the email address you are sending to is typed incorrectly. In this case, just make sure you have the email address spelled correctly.
Confirm with the recipient that you have their correct email address. If you have checked the email address and you are certain you typed it correctly, but you still get an SMTP 550 Error, then perhaps you got the wrong email address from the recipient. It could also be that they have changed the domain name or any other part of the address.
Check your own email address and message. Make sure that your sender email is typed correctly, and check that your email has content. Some email hosting servers can reject emails that are blank, or have no content.
Try changing your outgoing mail port to 26 or 465. Some servers block port 25 because spammers often use it to send spam, or spoofed emails.
Scan your computer for viruses and malware. Technically, email addresses don’t get infected; it’s the computers or the hard drives that do. Install a reliable antivirus program, and scan your computer. After the scan, change your email password, just in case you have been hacked.
Re-try sending the email after a few minutes, or hours. It is possible that the recipient’s server is just temporarily down and may come back up after a while. If you get the error message again, even after a few hours, contact the recipient and inform them that their hosting may be down.
Use your ISP’s outgoing mail server. Sometimes, it is your own Internet Service Provider or Internet gateway filtering and blocking your emails. If this is the case, you can try using your ISP’s outgoing mail server.
Contact your ISP. A good solution may be to ask your Internet Service Provider for assistance. After all, they are the one who know their system best, and may be able to help.
Change all your passwords. Be sure to use a random mix of letters, numbers, and special characters to make a really strong password. Also change your recovery options, since if hackers have gained access to your account they would probably aware of these options, too. As added protection, make a habit of changing your passwords regularly.
Email Problems: What Should I do?
How to Solve Email Bounce Back Issues
How Did My Email Get Compromised and What Can I Do to Stop It?
Managing the Mail Function in CPanel
What is Email Spoofing?
What is Spamming?
Other Possible Causes of "Error 500, No Such User Here"
Sender email or receiving email account is over-quota
Mail file permissions are not readable or are incorrect.
MX records are incorrect ( pointing to the wrong server ).
Email does not route correctly ( Remote / Local domains )
Sender or Receiving Email Account is Over-Quota
Full mailbox. Mailbox storage quotas are set to 250MB by default, but some plans allow you to turn off the limit and set mailbox quotas to "unlimited." If an email account is at or past its capacity, sending out from it won't work and you'll get a "Sender Verify Failed" error. To check on the mailbox quota of an email account follow these steps:
Log in to your Bluehost control panel.
Go to the Hosting menu and click Email in the submenu.
Locate the email address having problems in the list, and click view details button on the right to view detailed information about the email account.
Look for the mailbox quota. If the account is at or exceeding its quota, increase its limit or delete emails to save space.
Mail file permissions are not readable or are incorrect
All our servers store email in the "mail" directory of the "home" folder of your cPanel account. If the file permissions are corrupted ( sometimes caused by server moves, back up restorations, or recently uploaded files through FTP, etc.) you will get this error for all your emails. This is a simple fix. You can contact tech support to have the file permissions fixed on your server. On VPS and Dedicated servers, you can run the following from command line:
[root@vps#### ~]$ fixperms userna5
This will reset all your file and folder permissions to folders 755 and files 644 for the cPanel user userna5. If the email bounce is coming to you when you send to another server and it's permissions related, the person you are emailing will need to contact their hosting provider to fix the permissions on their end.
MX records are incorrect ( pointing to the wrong server )
If you recently moved your domain to Todhost Hosting and you started receiving these errors, you may have a DNS nameserver or MX record problem. The MX records point your email address to a specific server. If the MX record is pointing your domain to the old hosting company and you removed all your email accounts off that server, when you go to send your email, you will get the "550 No Such User Here" error.
Make sure your nameservers are pointing to us. If your nameservers do not point to our server, then your domain will not route to our server unless you make special DNS changes at the host the nameservers point to.
Make sure the MX records for your domain are sending to the correct server. If your domain does point to the correct server, check the MX records to see if the email is pointing to the correct server in the cPanel MX entry.
If your nameservers and DNS are correct, then you will need to check the email routing. If the bounce message is from you sending to another server, then the person receiving the email will need to check with their email provider for a resolution.
Email does not route correctly ( Remote / Local domains )
The email routing setting in your Zone Editor determines how outgoing email is handled for a particular domain. There are three possible settings:
Local Mail Exchanger. Use this setting if the domain's email is hosted by Bluehost, even if the domain uses third-party name servers.
Remote Mail Exchanger. Use this setting if the domain's email is not hosted by Bluehost and your MX records are pointed to a third-party email server.
Automatically Detect Setting. Use this setting if you aren't sure. The server will decide if the setting should be Local or Remote based on the MX record. This is usually not recommended.
It's important for the email routing setting to be accurate for each of your domains to prevent any delivery failure issues. Follow these steps to update your email routing settings:
In the DNS Zone Editor, choose your domain from the drop-down menu.
Scroll down to MX (Mail Exchanger).
Click More to expand the section.
Choose your setting.
Click Change to save.
How things go wrong with cPanel Remote Mail Exchanger
In cPanel servers, there is an option called “Email routing” which decides how mail is handled for a domain. By default, new accounts created on the server have mails handled by the same server. But when the domain needs to use another server for mail, the email routing has to be set as “Remote Mail Exchanger”.
Here’s how Email Routing is set for a domain in cPanel servers.
Mail server tries to send mails to another server after checking the Remote Mail Exchanger setting for the domain.
Listed below are the situations where mails fail due to this setting.
1. Remote Mail Exchanger not set
To enable external mail servers for a domain, website owners simply set the custom mail servers (MX) records for the domain.
Unfortunately, that is not enough for mails to show up in the external mail servers.
Mails from website forms or other domains hosted on the same server still fail. This happens as the mail server tries to deliver the mail within the server.
To fix the problem, set the correct email routing as per the MX records of the domain.
Also ensure that the correct values are present in the mail server configuration files like /etc/localdomains and /etc/remote domains as well.
2. Incorrect value for Remote Mail Exchanger
Cpanel maintains two domain lists :
Domains whose mails are on the same server
Domains whose mails are on remote servers.
When we change email routing for a domain, cPanel automatically adjusts these lists.
For example, when we set Remote Mail Exchanger for a domain, cPanel removes the domain from the local domains list and automatically adds it to the remote domains list.
But this may not always work due to bad server settings.
And when a customer wants to change their domain’s MX to a different provider, say Google, he will set MX in dns records and change email routing to “Remote Mail Exchanger”. Normally, this is enough for mails to show up at Google.
But if for some reason cPanel fails to remove this domain from the local domains list, the mail server will still try to deliver all mail from other domains on the same server locally. This will result in an email error “Recipient Not Found” as the original recipient exists at Google.
In such cases, for mail to work properly, our do the following :
Set mail routing to “Remote Mail Exchanger”
Remove entries for the domain from the list of local domains
Add the domain to the list of remote domains
This error can go both ways, meaning, people sending to your server may get the error and when you send from your server to another you may get the error. Depending on where the error bounce is generated from will determine what you can do about fixing the error.
If you get "550 No Such User Here" bounces sending an email from your server to another server, you most likely will need to contact the host or email administrator of the server you are emailing to fix it.
If you are getting complaints that people sending to your server are getting this bounce, you can check / change the settings on your server's end.