1. Home
  2. Documentation
  3. Campaigns
  4. Bounce types

Bounce types

Bounces are the emails that returned to the “return-path” address of the email if its delivery was unsuccessful at the recipient ISP. Mailfed tracks these bounces and send a copy to the From Email address of the sender to respect email standards – these can be processed by the users for some other applications as well.

There are mainly 3 category of bounces in Mailfed –


  1. HARD : These are the bounces generally returned with 5xx codes. This may represent a permanent delivery failure¬†– like the domain doesn’t exist or user doesn’t exist etc. Once a Hard bounce is captured by the system, it will mark that subscriber as “Blacklisted” on the very first occurrence on the list to which the campaign was done. No further mailing will be done to this subscriber. If the same subscriber is present in another list and that’s not Blacklisted yet, mailing can happen.
  2. SOFT :¬†These are the bounces generally returned with 4xx codes. This represents a temporary error such as user mailbox full or any technical issues at the receiver’s side. System will mark such a subscriber as “Blacklisted” only if it encounters 5 such SOFT errors for the same list.
  3. INTERNAL : There are no specific error code for this – it can be 4xx or 5xx – should be 4xx ideally. INTERNAL bounces are a result of SPAM protection at the receiving side. They might bounce the emails due to various reasons such as spammy content, low IP reputation, presence of the source IP in DNS blacklists etc. Because these errors are temporary and can be avoided, system will not mark such subscribers as “Blacklisted” at any point of time – mailing can continue.
Was this article helpful to you? Yes No