When you send emails from Dualoo, we receive feedback from our provider as to whether the email was delivered. If this was not possible, we will inform the sender of the email with information about the reason for non-delivery, with the subject line "[Dualoo] An email could not be delivered":
The error message contains the reason for rejection by the recipient. These are usually very technical and vary depending on the email provider. However, they usually provide a note about the problem and how to fix it. We have therefore listed some reasons in this article to make them easier to interpret:
Email domain does not exist
Email domain could not be found. This is usually due to a typing error in the domain, e.g. gmial.com instead of gmail.com. In many cases, you will find the error relatively quickly and can correct the email address with the candidate. Otherwise, contact the candidate by another means.
Error message:
error dialing remote address: dial tcp 168.245.17.9:0->185.46.58.149:25: i/o timeout
error dialing remote address: dial tcp 168.245.17.9:0->213.3.75.39:25: connect: connection refused
unable to get mx info: failed to get IPs from PTR record: lookup : unrecognized address
unable to get mx info: failed to get IPs of MX record: The ip address resolved to a BOGON address
error dialing remote address: dial tcp 168.245.17.9:0->213.3.75.39:25: connect: connection refused
unable to get mx info: failed to get IPs from PTR record: lookup : unrecognized address
450 4.1.8 : Sender address rejected: Domain not found
Email address does not exist
The email address does not exist under this domain. This is usually due to a typing error in the part before the domain, e.g. lulas.locher@ instead of lukas.locher@.
Error message:
550 5.1.1 MXIN501 mailbox [email protected] unknown ;id=Y9gysftH3cz4qY9gzs76Zk;sid=Y9gysftH3cz4q;mta=mx4-prd-nl1-sun;d=20240728;t=213629[CET];ipsrc=168.245.17.9;
550 5.1.1 The email account that you tried to reach does not exist. Please try double-checking the recipient's email address for typos or unnecessary spaces. For more information, go to https://support.google.com/mail/?p=NoSuchUser 3f1490d57ef6-e0b2a92f9desi4178607276.304 - gsmtp
550 5.1.1 : user does not exist
550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient not found by SMTP address lookup
550 5.0.0 [email protected]... No such user
550 5.1.1 <[email protected]> recipient rejected, address unknown
550 no such address here
550 5.5.0 Requested action not taken: mailbox unavailable (S2017062302).
550 5.4.1 Recipient address rejected: Access denied.
552 1 Requested mail action aborted, mailbox not found
Mailbox has no more storage space
The recipient's mailbox has no storage space available and the emails will not be delivered.
Error message:
552 RCPT TO: Mailbox disk quota exceeded
552 5.2.2 <[email protected]> Quota exceeded (mailbox for user is full)
552 5.2.2 <[email protected]>: user is over quota
452 4.2.2 The recipient's inbox is out of storage space. Please direct the recipient to https://support.google.com/mail/?p=OverQuotaTemp d75a77b69052e-454fe0d2869si92277131cf.76 - gsmtp
554 5.2.2 mailbox full; STOREDRV.Deliver.Exception:QuotaExceededException; Failed to process message due to a permanent exception with message [BeginDiagnosticData]Microsoft Unified Storage is full. QuotaExceededException: Microsoft Unified Storage is full.[EndDiagnosticData] [Stage: DeliverMessage]
552 1 Requested mail action aborted, mailbox not found
Email server rejected email
The email server has rejected the email. If the recipient is a candidate, another channel must be used for communication. If emails have been successfully delivered in the past, please contact our support team.
If the recipient works at your company, add our domain to your email whitelist. The best way to do this is to contact our support team here.
Error message:
550 5.7.350 Remote server returned message detected as spam
550 5.7.1 Unfortunately, messages from [159.183.225.213] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [Name=Protocol Filter Agent][AGT=PFA][MxId=11BB0C3654E44C79] [SJ5PEPF000001F7.namprd05.prod.outlook.com 2025-04-28T06:22:32.460Z 08DD861B2A735D6F]
550 permanent failure for one or more recipients ([email protected]:blocked)
554 sorry, Spam detected by SpamAssassin (#5.3.4)
If you have questions about a specific error message, please contact our support team.