Catch-all is also known as an “accept all.” This is a domain-wide setting where all emails on this domain will be reported as a catch-all. There is no definitive way to determine whether this email is valid or invalid.
A catch-all address is commonly used in small businesses to ensure a company receives any email that has been sent to them, regardless of typos. Additionally, these are also found in larger government, medical and educational organizations. Oftentimes these are infact valid emails. However, some organizations may utilize this setting as a security feature to prevent unsolicited emails.
SAFE – If you have a dedicated email server with your own IPs, catch-all emails may be safe for sending dependent on the overall health of your list.
DON’T SEND – If you use a third-party email provider that requires a bounce rate below 4%, these emails are not safe for sending.
The More You Know...
The percentage of Catch-alls is directly correlated to the amount of "Invalid" emails within a set of data. The higher the invalid rate, the more likely the catch-alls are to bounce. If you have a fairly clean list, the catch-alls have a better chance of being "valid" results.
We have noticed catch-alls tend to bounce at half the rate of your original invalid percentage. So for example, if you had 10% invalids within your list, it is possible up to 5% of your catch-alls will still bounce. This is a very important to be aware of when it comes to sending to catch-alls.
If your data was not purchased, and you have a pretty good idea where it came from, you should have a less likely problem with bounces rather than data that you are unsure of or that you purchased.
I am able to share some safe sending practices when it come to the Catch-all result code.
Sending in small batches (at your discretion) and monitoring which ones bounce back (these will be emails you will want to take out of your data) can help you begin extracting invalid emails from your list. Some ESP's will allow a higher amount of catch-alls to be sent at once, but we would recommend contacting the sending platform of your choice to gather any additional information. We also recommend using another email account to do some catch-all sending in order to see which ones bounce back (these will be invalid, and the emails that don't bounce most likely made it through to their intended destination) this way you will not hurt your sending status with your primary email account or sending platform.