Likewise, when sending email from an IP address not available in SPF record, it results in a delivery status notification sent to the original sender. If the email originates from an IP listed in the SPF record, the recipient server accepts mail. This SPF record contains the IP addresses of servers that can send emails on behalf of the domain. Reason: SPF check is an anti-spam measure to check the SPF (Sender Policy Framework) record of the domain to verify whether the sender is genuine or not. SPF records are used to prevent any mail forgery, email spoofing, etc.īounce back: Message Rejected Due To: Spf Fail If your mail server's domain name were, then you would ask your ISP to set up a reverse PTR record for your mail server and give them the IP address of the server.

How to fix? If you need a PTR Record(rDNS) set up for your mail server you'll need to contact your mail service provider as this is something they'll set up for you.

Reason: This is a bounce-back message when the emails are getting rejected since the rDNS record of the IP of your email server is not matching with the forward DNS or if there is no rDNS record setup at all. We are doing some additional checks at Flockmail server to prevent incoming email spamīounce back: 450-'4.7.25 Client host rejected: cannot find your hostname, ' It's a good practice to regularly determine your IP reputation on a tool like. How to fix? You may have to bring this issue to your ISP's notice and get the IP whitelisted. Reason: This is a bounce-back message that you receive stating that the client IP is blacklisted and untrustworthy. How to fix? Please confirm that there are no typo errors in the email address and is a valid, existing email.Įvery email originates from a particular IP address and gets ranked according to their reputation.īounce back: Incoming email server rejected the email since the client IP(From IP): .xx is blacklisted, hence considered as spam Reason for reject: This error message shows that emails are not delivered to the mailbox the mail server can’t find this email account on the server. NOQUEUE: reject: RCPT from : 550 5.1.1 : Recipient address rejected: User unknown in virtual mailbox table from= to= proto=ESMTP helo= : Recipient address rejected: User unknown in virtual mailbox table This is one of the common errors in Postfix mail servers when users send emails to their local mailboxes.īounce back: 550. Mails getting detected as spam by the spam filter.Here are a few of the most common bounce back messages that you may encounter during email sending or receiving:

Custom email bounce back message