A soft bounce is an email marketingEmail marketing, also known as Emailing, is a digital marketing strategy that uses email as its medium. It is one of the... More concept.
It refers to a notification which indicates that a message sent has not been received successfully. In contrast to a hard bounceA hard bounce is an email marketing concept. It refers to a notification which indicates that a message sent has not bee... More, a soft bounce is a temporary notification of failure, which indicates that the address concerned was unable to receive the email sent at the time of sending, but also that the receiving address does exist.
There are several possible causes of a soft bounce, the main ones being :
– a recipient SMTPSMTP stands for “Simple Mail Transfer Protocol”. Created in 1982, SMTP is an email transfer protocol used for... More server that was down or malfunctioning when the email was sent
– an overloaded recipient SMTP server when the email is sent
– the recipient’s mailbox is full and cannot receive any other emails
– a temporary blockage of the email sent because the sender IP or domain is considered suspicious
– a temporary blockage of an email sent because too many emails have been sent to the same domain too quickly
– a temporary blockage of an email sent based on suspected spam content.
Whatever the reason for the blockage, the soft bounce notification indicates that the content of the email could not be delivered to the recipient, and that the sending server has stopped trying to deliver it (i.e. the message has not been received and will not be, unless you ask for it to be sent again).
Like hard bounce, a soft bounce is generally sent to the email addressEmail addresses, also known as "electronic addresses" or simply "emails", represent a form of digital communication popu... More from which the message originates (header “FROM:” field), by the SMTP server which was supposed to receive the email (header “TO:” field).
Given the multiple possible causes that can generate this type of bounce, different return codes will be used by SMTP servers to indicate that this is a soft bounce, mainly in the “45x” code range (e.g. the message “450 mailbox overquota” for a full mailbox).
As with hard bounces, email routersAn email router is an online service that simplifies and enriches (through statistics and tracking) the email marketing ... More monitor their customers’ average soft bounce rates, to detect possible deliverability problems on sending domains or IPs. An excessively high soft bounce rate is therefore an important metric that often indicates a degraded reputation of the sender domain, and is associated with recurring problems in sending emails.
Unlike hard bounces, soft bounces are created within a specific configuration (which was used when sending the message), and therefore do not indicate an invalid mailbox. They therefore indicate a problem in the delivery of that specific email, and not an invalid recipient mailbox status.
So they will not necessarily be detected by an email checkerAn email verifier, also known as an email checker, is a software used to check an email address or a list of email addre... More, which primarily detect invalid emails (hard bounce). It should be noted, however, that certain types of soft bounce can be detected by good quality mail testers (e.g. emails with a mailbox full).