To help you better understand why a message bounced, we categorize bounces into different bounce categories. Below is a breakdown of the category, the short description included within the Outreach platform, and a longer description which provides a bit more detail.
Flagged as Spam
Outreach Short Description: “This message was flagged by spam by the recipient’s mailbox”
Every email that lands in your prospects inbox can be marked as spam. This message indicates that either your email was flagged by your customer’s IT team as spam because it did not meet their criteria to pass through to the designated mailbox, or your customer clicked on the “mark as spam” button when they saw your email in their inbox.
These emails should not be retried, since they will continue to bounce and potentially affect your email deliverability.
Outreach Short Description: “The recipient email address does not exists”
The bounce message tells us that the email address was either entered incorrectly or is no longer an active mailbox (i.e. the prospect has left the company). This error is specific to the local part and/or email domain. The local part is the text found on the left of the @ symbol (rsiegel@), and the domain is the text found on the right of the at symbol(@outreach.io). If you believe this bounce message was received in error, make sure that the domain is spelled correctly and has the right domain end (.io, .com, .org, .edu, etc.). If the domain is correct, make sure the local part is correct (rachael.siegel@ vs resiegel@ vs rsiegel@). If the bounce error persists, then it is likely that the prospect has left the company and their emails are not being forwarded to another individual, such as a colleague or their manager.
It is possible, though unlikely, that the prospect’s email account has been suspended and is temporarily unable to accept emails.
Outreach Short Description: “The recipient’s mailbox is full and cannot accept accept messages”
Some organizations set a limit on the number of emails an individual can have in their inbox at one time. Once the individual clears out old messages from their inbox, either by moving them into different folders or deleting them entirely, they’ll be able to receive new email. This is a temporary error, so emails that receive this bounce category can be safely retried.
If you continue to receive this error after attempting to redeliver, it’s likely the email address is no longer in use.
Rejected by Recipients Mailbox
Outreach Short Description: “This message was rejected by the recipient's mailbox due to a policy violation or security error”
Bounce messages that are rejected with this error are rejected due to the administrative settings the prospect’s company’s IT team has enabled as protection against unvetted senders.
Rejected due to Message Size
Outreach Short Description: “This message exceeded the maximum size the recipient's mailbox accepts.”
This bounce message is letting you know that your email was not delivered to your prospect because it is too big. Size limits are set by the prospect’s company’s IT team, who do not provide visibility into what, specifically, is causing the email size to exceed the limit. This is often a combination of email elements, including the amount of text, attachments, and embedded images.
Alternatively, it’s possible that a single element, such as an attachment, is too large. Outreach recommends a combined email size of no more than 5MB, including images and attachments. We’d also suggest compressing images into smaller files. A balance of text with images and attachments are best practice for email deliverability.
Unable to Connect to Recipient Mailbox
Outreach Short Description: “Message delivery was delayed by recipient's mailbox. Try again.”
In some cases, bounces are caused due to an error from the prospect’s server. Unlike other bounce reasons, these are usually temporary errors and the bounced email can be retried for successful delivery.
Unable to Determine Bounce Reason
Outreach Short Description: “Not enough information to determine bounce reason.”
Bounce reasons are provided by your prospect’s company’s mailbox policies, which are set by IT Administrators. In most instances, some information is provided within the bounce message, which is where the bounce reason is provided. Bounce reasons are optional, so not every company will provide detail into why your message could not be delivered. If you received this bounce category, we either do not have enough detailed information about the email bounce to determine the cause, or the bounce reason is not in english.