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Beginner

5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

Dear all

i got 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed this kind of message when i send email to example@domain.com. But other domain successfully accepts email. only this domain send this message back

5 REPLIES 5
Cisco Employee

Re: 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

Hi, 

 

It might be possible that the destination server is rejecting your emails based on the DNS records not being published for the email address used to send emails.
You can check the DNS records.

 

If the DNS records are fine then you would need to check with the destination domain to know the criteria they are using for your domain.

 

Thanks

Amrita

Beginner

Re: 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

thanks for your reply. When i check dns issue using mxtoolbox is seems it is ok.

what the interesting part is that i didn't do anything but email reaches to destination properly. i didn't understand that where was the problem. 

Cisco Employee

Re: 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

This usually occurs because of some restrictions at the destination server.

 

If possible reach out to destination server to find why they are rejecting your emails.

Beginner

Re: 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

i called when this issue occurred they said that they have now any problem by getting email by other domains. what is your recommendation if this problem happens again. what at first i have to look at in my side before calling other side?
Cisco Employee

Re: 5.0.0 smtp; 5.1.0 - Unknown address error 550-"Verification failed

Hello ccns90,

“Verification Failed.”
As the previous responders may have mentioned, check your sending server credentials.

The ESA has a feature within the Mail Flow Policies called “Sender Verification.”
Other Mail Gateways may have this same or similar feature on their product.


You can open the ESA built in Help Guide to learn more.
Browse to the Top right corner select > HELP AND SUPPORT > Online Help
When the page opens search for “Verifying Senders.” >> the name “Verifying Senders” should be visible in the far left Contents menu.
I pasted the basics below, but this has additional content of value if to to the page.

Verifying Senders

Spam and unwanted mail is frequently sent by senders whose domains or IP addresses cannot be resolved by DNS. DNS verification means that you can get reliable information about senders and process mail accordingly. Sender verification prior to the SMTP conversation (connection filtering based on DNS lookups of the sender’s IP address) also helps reduce the amount of junk email processed through the mail pipeline on the appliance.

Mail from unverified senders is not automatically discarded. Instead, AsyncOS provides sender verification settings that allow you to determine how the appliance handles mail from unverified senders: you can configure your appliance to automatically block all mail from unverified senders prior to the SMTP conversation or throttle unverified senders, for example.

The sender verification feature consists of the following components:

* Verification of the connecting host. This occurs prior to the SMTP conversation. For more information, see Sender Verification: Host<>.
* Verification of the domain portion of the envelope sender. This occurs during the SMTP conversation. For more information, see Sender Verification: Envelope Sender<>.

Enjoy reading,
Chris A