cozz
Level 1: Cadet

Failing to send emails - 550 error

Answered

Hi, 

 

I have been having intermittent issues in sending emails for a few weeks.  Now it is occurring all the time.  I have a Telstra business DSL connection and was instructed to use smtp.telstrabusiness.com as the SMTP server.  No authentication and on port 25.  This has been working up until recently. 

 

The error I am receiving is below - 550 sender rejected.  This error is occuring across multiple PCs sending emails from our network.  Our IMAP server is not hosted by Telstra, I have no issue in receiving email. 

 

I have read on these forums to use authentication when sending.  My Telstra DSL login has domain @direct.telstra.net and authentication when sending via smtp.telstrabusiness.com does not authenticate.  

 

I have tried sending via mail.bigpond.com with and without authentication.  This has the same result.

 

I am wondering if my domain has been blacklisted? Not sure how to check this and seek your advise.  Thank you in advance. 

 

*edited due to guidelines*

1 ACCEPTED SOLUTION

Accepted Solutions
Technical Support
Technical Support
Accepted Solution

Re: Failing to send emails - 550 error

Hi Cozz, 

 

The image that you posted shows an error message: Sender rejected. OB506 

 

This means your outbound (OB) mail is being rejected because your domain name or IP address is listed on the Invaluement DBL (Domain Black List). Which is why you are unable to send outgoing mail (Sender rejected).  

 

How did this happen?
Basically, Invaluement has detected undesirable activity in relation to your domain name and blocked it. Most domains are listed as a result of directly sending spam or viruses to special detectors (spamtraps) or by initiating SMTP transactions that look similar to viruses or botnet-proxies.

 

What Can I Do?
Your system is very likely compromised by a virus either via mail, the web, or other download. So the first step is to determine whether your computer or any other devices connected to your service is sending out spam or infected by a virus. If you’re absolutely sure that nothing under your control is sending out spam or has a virus, then visit the blacklist removal page on the Invaluement website, and request the removal of your address (a delist request). You can also check your domain or IP here as well.

 

I can’t stress enough how important it is to verify that you’re not actually sending spam. In many cases if your IP address has been blacklisted, the cause is a device within your own home or office network, which has been compromised and is sending spam. If you don’t fix the spam sending problem, then any attempt to move to a new IP address or de-list your listing will quickly fail and may lead to more severe listings.

 

Please note, I've also deleted the image for privacy reasons.

Need help? Check out our Community Wiki or Support Portal || Looking for a new mobile? Order online today || Get help with any Tech at Home with Telstra Platinum || Don't forget to tag answers as Accepted Solutions and give a Like to the member(s) who helped you out.

All moderation actions are supported by the CrowdSupport Community Guidelines

Was this helpful?

  • Yes it was, thank you
  • No, I still need help
2 REPLIES
Technical Support
Technical Support
Accepted Solution

Re: Failing to send emails - 550 error

Hi Cozz, 

 

The image that you posted shows an error message: Sender rejected. OB506 

 

This means your outbound (OB) mail is being rejected because your domain name or IP address is listed on the Invaluement DBL (Domain Black List). Which is why you are unable to send outgoing mail (Sender rejected).  

 

How did this happen?
Basically, Invaluement has detected undesirable activity in relation to your domain name and blocked it. Most domains are listed as a result of directly sending spam or viruses to special detectors (spamtraps) or by initiating SMTP transactions that look similar to viruses or botnet-proxies.

 

What Can I Do?
Your system is very likely compromised by a virus either via mail, the web, or other download. So the first step is to determine whether your computer or any other devices connected to your service is sending out spam or infected by a virus. If you’re absolutely sure that nothing under your control is sending out spam or has a virus, then visit the blacklist removal page on the Invaluement website, and request the removal of your address (a delist request). You can also check your domain or IP here as well.

 

I can’t stress enough how important it is to verify that you’re not actually sending spam. In many cases if your IP address has been blacklisted, the cause is a device within your own home or office network, which has been compromised and is sending spam. If you don’t fix the spam sending problem, then any attempt to move to a new IP address or de-list your listing will quickly fail and may lead to more severe listings.

 

Please note, I've also deleted the image for privacy reasons.

Need help? Check out our Community Wiki or Support Portal || Looking for a new mobile? Order online today || Get help with any Tech at Home with Telstra Platinum || Don't forget to tag answers as Accepted Solutions and give a Like to the member(s) who helped you out.

All moderation actions are supported by the CrowdSupport Community Guidelines

cozz
Level 1: Cadet

Re: Failing to send emails - 550 error

Thanks Kenobi.  My website was compromised 2 weeks ago and may have something to do with this.  I deleted the active components of that site last week and put up some static pages so believe the issue should not be further occuring.  

 

I had searched our domain for blacklisting but was unable to find anything.  I was in the process of adding SPF and DMARC records to the domain as i thought this may have been the issue (identified through one of your previous posts) 

 

I will submit a request to delist on Invaluement now.  Thanks again for your advice.

Goodbye Excess Data Charges

Hello New Plans.

Find out more