Bounce processing protects the integrity of email lists by ensuring they are clean and current. The result is higher deliverability since ISP’s regard repeated attempts to deliver to nonexistent addresses as spamming or harvesting.
For our customers convenience; our systems automatically categorized bounces into a number of different types so different actions can be taken for different bounce types.
A Blocked message/recipient occurs when our system prevents a message from being sent. To identify the reason for the blocked message, either review the “Message Tracking” details or download the “Recipient Bounce Details” data file and review the “details” column. The most common cause for a blocked message/recipient is due to a Hard Bounce address or a blocked keyword. (Either of the two reports will provide all information necessary to identify the root cause)
A hard bounce occurs when the recipient’s mail server replies with a permanent error (typically 5xx codes), which in most cases means that the attempt to deliver to that recipient will never succeed. An example of a hard bounce error is ‘firstname.lastname@example.org’ does not exist, which commonly occurs when a list of members has not been contacted recently.If you receive a hard bounce, you should immediately remove the recipients from any future mailings.
A soft bounce occurs when the recipient’s mail server replies with a transient error (typically 4xx codes), or never replies at all. An example of a soft bounce error could be caused by a server that overloaded or a user whose mailbox is full.As a general rule, if you receive 5 soft bounces for a recipient you should remove them from any future mailings.
Greylisting (or graylisting) is a method of defending e-mail users against spam. A mail transfer agent (MTA) using greylisting will “temporarily reject” any email from a sender it does not recognize. If the mail is legitimate the originating server will, after a delay, try again and, if sufficient time has elapsed, the email will be accepted.Unified eMail servers will automatically retry delivery after a delay.
UBL Bounce (User Block List)
Numerous ISPs and corporate mail systems allow individual Users to block inbound mail from select recipients or URLs within the content of the message. Bounces classified as UBLs fall into this category.
The message was blocked due to a sending IP address being blocked by the recipients server. This may be caused by an eMail administrator explicitly blocking the sender’s server or because the sending server’s IP is listed on a public RBL provider.
Unified eMail monitors over 170+ public RBLs. If any of our shared or dedicated IP addresses ever shows up; our support staff works with the RBL provider to get it removed as soon as possible. Unified eMail also monitors to see if any recipient server is blocking delivery. In the event an individual recipient server blocks mail delivery; our support staff will attempt to contact the eMail administrator of the recipients domain to remove the blocking.
A technical issue prevented delivery of the message.
Our systems were unable to classify the bounce. (Typically the response from the recipients server was not recognized)