Fix outgoing email rejection errors in Titan When Titan rejects an outgoing message, the error contains a code and a description of the problem. This article helps Titan mailbox users and domain administrators match the complete error text to its cause and apply the correct fix. Some fixes require access to your domain's Domain Name System (DNS) settings, where Sender Policy Framework (SPF) and DomainKeys Identified Mail (DKIM) records are managed.
| Reply Code |
Status Code |
Error Message : Eg |
Explanation |
| 504 |
5.5.2 |
504 5.5.2 <user@example>: Sender address rejected: need fully-qualified
address
|
Mail rejected as the MAIL FROM address is not in fully-qualified
domain
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Hourly Quota Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Daily Quota Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Domain Daily Limit Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
50 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Domain Hourly Limit Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
50 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Domain Hourly Bounce Limit Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
50 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Domain Daily Bounce Limit Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Daily Bounce Limit Exceeded
|
Bounce limit exceeded
https://support.titan.email/hc/en-us/articles/900001359746-Email-Bounce-Back
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Hourly Bounce Limit Exceeded
|
Bounce limit exceeded
https://support.titan.email/hc/en-us/articles/900001359746-Email-Bounce-Back
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender Daily Forward Ratelimit Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive?utm_campaign=Titan+Support&utm_source=support-email
|
| 550 |
5.4.6 |
550 5.4.6 <user@domain.com>: Recipient address rejected: Sender
Domain Daily Unauthenticated Mails Sent Quota Exceeded
|
Ratelimit exceeded
https://support.titan.email/hc/en-us/articles/360038836914-How-many-emails-can-I-send-and-receive?utm_campaign=Titan+Support&utm_source=support-email
|
| 550 |
5.4.6 |
550 5.4.6 An email sent to this address has been rejected with the
reason 'Mailbox does not exist' within the last 30 days. Check for
typos in the email, or ensure that this subscriber is not a part
of your mailing list. To send an email to this address, contact the
support team once you are sure the mailbox has been created
|
We have recently got a feedback from the email service provider that
, this email is an non-existing email. If this is a newly created
email . Please get in touch with support@titan.email
|
| 550 |
5.8.1 |
550 5.8.1 Error in dkim public key,invalid dkim key format. Please refer Set up DKIM Record
|
The DKIM key added to your DNS panel might have some incorrect values or incorrect formatting. Please ensure that you copy the exact DKIM value from the Control Panel. Once your DKIM key is reverified it may take some time to reflect the changes which should be up to your DNS TTL.
https://hubs.li/Q02gVWn70
|
| 550 |
5.8.1 |
550 5.8.1 Error in dkim public key,DKIM public key not found in dns. Please refer Set up DKIM Record
|
The DKIM public key record from your DNS is missing.Most commonly it can happen due to some mistake while configuring dns records manually. We request you to add back the same and then attempt to send an email.
https://hubs.li/Q02gVWn70
|
| 550 |
5.8.1 |
550 5.8.1 Error in dkim public key,more than one txt record in same selector. Please refer Set up DKIM Record
|
The DKIM public record added to your DNS has more than one TXT value. Titan doesn't allow multiple dkim key records to avoid conflicts under same selector. Hence, please ensure that you paste the exact value from the Control Panel. Once your DKIM key is reverified it may take some time to reflect the changes which should be up to your DNS TTL
https://hubs.li/Q02gVWn70
|
| 550 |
5.7.2 |
550 5.7.2 <user@domain.com>: Sender address rejected: SPF Policy of your domain doesn't explicitly allow us to send email on your behalf
|
Your domain has an SPF record that is not configured to allow Titan to send emails on your behalf.
https://support.titan.email/hc/en-us/articles/27756794870169-Email-Authentication-Measures?utm_campaign=Titan+Support&utm_source=customer-support
|
| 550 |
5.7.5 |
550 5.7.5 <user@domain.com>: Sender address rejected: SPF Record for your domain is not set up. Please refer to this Email Authentication Measures
|
You domain does not set up the SPF record
https://support.titan.email/hc/en-us/articles/27756794870169-Email-Authentication-Measures?utm_campaign=Titan+Support&utm_source=customer-support
|
| 550 |
5.7.4 |
550 5.7.4 <user@domain.com>: Sender address rejected: SPF Record for your domain is not proper. Please refer to this Email Authentication Measures
|
There is a syntax error in your SPF record, or there are multiple SPF records
https://support.titan.email/hc/en-us/articles/27756794870169-Email-Authentication-Measures?utm_campaign=Titan+Support&utm_source=customer-support
|
| 550 |
5.7.1 |
550 5.7.1 message content rejected |
https://support.titan.email/hc/en-us/articles/360038836754-Why-are-email-with-attachments-not-working
|
| 552 |
5.3.4 |
552 5.3.4 Message size exceeds fixed limit |
https://support.titan.email/hc/en-us/articles/360038836754-Why-are-email-with-attachments-not-working#:~:text=2.-,File%20size%20exceeding%20the%20size%20limit,should%20not%20exceed%2030%20MB.
|
| 550 |
5.4.7 |
5.4.7 SenderAliasDenied: You are not allowed to send email from user1@domain1.com.
as user2@domain2.com
|
User is attempting to send as different user than the logged in user,
which is considered as a phishing attempt
|
| 550 |
5.7.1 |
5.7.1 Message Rejected: Invalid From address. Different domains domain1.com and domain2.com found
|
The user is attempting to send an email as a different user than
the one logged in, which is considered a phishing attempt.
|
| 550 |
5.4.8 |
5.4.8 SenderAccountDenied: Account not found; from=<user1@domain.com>
to=<user2@domain.com>
|
The user is attempting to send an email as a different user than
the one logged in, which is considered a phishing attempt.
|
| 550 |
5.7.1 |
5.7.1 Message Rejected: Invalid From address. Invalid domain name
in from address:
|
The user is attempting to send an email as a different user than
the one logged in, which is considered a phishing attempt.
|
| 550 |
5.4.6 |
5.4.6 SenderRecipentDenied: You are not allowed to send email to
user@domain.com for the possible reason of abuse
|
Once we receive a spam or ARF complaint, we block the sender from
sending any further emails to that recipient.
|
| 550 |
5.7.1 |
5.7.1 Mail is compromised image |
The content filter categorizes the email as spam, phishing, virus
or compromised.
|
| 550 |
5.7.1 |
5.7.1 Mail is compromised domain |
The content filter categorizes the email as spam, phishing, virus
or compromised
|
| 550 |
5.7.1 |
5.7.1 Mail contain virus Malicious UR |
The content filter categorizes the email as spam, phishing, virus
or compromised
|
| 550 |
5.7.1 |
5.7.1 Mail contain phishing content Other |
The content filter categorizes the email as spam, phishing, virus
or compromised
|
| 550 |
5.7.1 |
5.7.1 Mail contain virus Malicious URL |
The content filter categorizes the email as spam, phishing, virus
or compromised
|
| 550 |
5.7.1 |
5.7.1 Mail contain spam content |
The content filter categorizes the email as spam, phishing, virus
or compromised
|
| 553 |
5.7.1 |
553 5.7.1 <user@domain.com>: Sender address rejected: not owned by user user2@domain.com
|
User is attempting to send as different user than the logged in user,
which is considered as a phishing attempt
|
| 553 |
5.7.1 |
553 5.7.1 <user@domain.com>: Sender address rejected: not logged
in
|
User attempting to send without authentication |
| 554 |
5.7.1 |
554 5.7.1 <user@example.com>: Recipient address rejected: Mail
to this domain is not accepted
|
User is attempting to send mail to titan bounce feedback domain,
which doesn't accept mail
|
Confirm the issue is resolved
- Complete the recommended fix and wait for any sending limit or DNS update period to pass.
- Send one test message to a known, valid recipient.
- Confirm that Titan accepts the message and the same rejection does not appear.
- If a different error appears, copy the new complete message and search for that text instead.
What success looks like
Titan accepts the test message for sending and the original rejection no longer appears. This confirms that the sending error is cleared, but it does not guarantee that the recipient's provider will place the message in the inbox.
Troubleshooting
Problem: Your rejection message does not match any entry in this article.
Cause: The response may be new, shortened by the sending app, or returned later by the recipient's email provider.
Fix: Copy the complete message from the rejection or non-delivery notification. Check the Email Bounce Back guide.
A DNS error remains after you updated the record
Problem: Titan still reports an SPF or DKIM error after you changed DNS.
Cause: The update may still be appearing across DNS providers, may have been added in the wrong DNS manager, or may conflict with another record.
Fix: Allow up to six hours for DKIM changes, confirm the record is in the DNS manager that hosts your domain's records, remove duplicates, and verify the status again in Titan.
A content or limit error appears unexpectedly
Problem: You receive a security or volume rejection even though you did not knowingly send the affected messages.
Cause: A connected app, website, plugin, or unauthorized user may be sending from the mailbox.
Fix: Change the mailbox password, review connected apps and website plugins, pause automated sending, scan affected devices or websites.