Soft Failures — Block

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A block failure occurs when an email recipient's mailbox provider intentionally refuses a message. For example, the mailbox provider may refuse the connection, refuse to accept the email during the connection, or return the email as undelivered after several delivery attempts. Block failures may occur for multiple reasons, such as if the sending IP address is on an external blacklist or the SPAM complaint rate for the sender is high.

Note: This may be the result of other mailings sent from other clients and not directly related to the one you sent. However, if you see these types of failures, please note the best practices outlined in this section to minimize them in future mailings.

An email message may return a block failure if the recipient flags email sent through the IP address as SPAM. A block failure of SPAM Complaint may indicate one of several conditions.

  • The recipient may not be actively engaged with your organization, as evident through no or low opens or clicks. Inactivity directly correlates to SPAM complaints. We recommend you attempt to engage inactive recipients with a separate reactivation mailing and purge non-respondents from your lists. To create this mailing, identify inactive recipients who have not opened or clicked in mailings over the past six months and then send those recipients messages over the next 30 days to remind them of the relationship and allow for recipients to opt out of future email. After the 30 day window, send recipients with no open or click activity one final "Sorry to see you go" message that allows them to opt in, and then remove them from mailing lists.

  • You may email the recipient too frequently or not frequently enough. If you email too frequently, the recipient may identify the email as SPAM. If you email too infrequently, the mailing may not cause the recipient to remember giving you permission to send to them. We recommend you review the frequency of your mailings and adjust it as necessary to be consistent with recipient expectations. You should also offer recipients a choice on both frequency and content and then verify recipients understand what they sign up to receive, including the frequency of when to expect email.

  • The email message may not target its recipients appropriately, or its content is not relevant to the recipient's preferences. We recommend you provide sample email for recipients to review during the sign-up process and allow them to update their profiles with information used to increase the content's relevance.

  • The recipient may not associate the email with your organization due to poor branding. We recommend you use consistent, prominent branding in the 'From' address, 'From' name, and subject line.

  • The recipient may not associate the email with permission granted to your organization, a third-party you use for list rental, or an affiliate program. We recommend you use explicit methods to obtain and disclose permissions, such as through a double opt-in feature. To remind recipients of why they receive messages, you should prominently display permission statements in the mailings to explain that recipients subscribed to the mailing list. You should also reconfirm the permission or track other indicators of sustained interest such as responses and donations. We recommend you also investigate permission practices of affiliates and send follow-up messages to recipients to confirm consent before you add third-party names in lists.

  • The recipient may assume the mailing is the same as a similar mailing they have already opted out of. We recommend you create email campaigns and newsletters around distinct topics to help recipients identify which they want. You should also properly design email and enewsletter templates to handle opt-outs for specific messages and campaigns in the proper hierarchy.

An email message may return a block failure if its domain name or IP address appears on an external blacklist. A block failure of Blacklist may indicate one of several conditions.

  • The message may have generated a high rate of SPAM complaints.

  • The recipient email address may be a SPAM trap. SPAM traps are email addresses that once belonged to recipients but were closed or intentionally published on websites. Rather than reissue the addresses to recipients, mailbox providers mark them as traps to identify senders who attempt to send messages to them. We recommend you know your data sources and keep your list management practices current and active. You should investigate how third parties or affiliates compile and manage their lists. We also recommend you clean your mailing lists as part of your normal email management practices and send messages to recipients to confirm consent before you add third-party names in lists. For more information, see SPAM Traps

    Note: To help prevent delivery to SPAM traps, our system automatically suppresses known bad email addresses.

  • The recipient may assume the mailing is the same as a similar mailing they have already opted out of. We recommend you create email campaigns and newsletters around distinct topics to help recipients identify which they want. You should also properly design email and enewsletter templates to handle opt-outs for specific messages and campaigns in the proper hierarchy.

An email message may return a block failure if its domain name or IP address appears on a blacklist. A block failure of ISP Block may indicate one of several conditions.

  • The message may have generated a high rate of SPAM complaints.

  • The message may have generated a high rate of failures associated with SPAM or poor list management practices.

An email message may return a block failure if some aspect of its content triggers a SPAM filter, such as due to prohibited words or phrases or too many HTML tags, images, or font styles, sizes, or colors. We recommend you send your content through a SPAM score test. Based on the score, you can then assess your email templates and adjust the templates, style, and HTML as necessary.

Note: There are hundreds of SPAM filters, and most have low penetration and no appreciable impact on email delivery. Others may have broader impact depending on usage at the domains on your mailing list. Mailbox providers now rely less on content blocks and instead use other factors, such as the sender's overall reputation, to determine whether to accept email and deliver it to the recipient's inbox or junk mail folder.

An email message may return a block failure if a URL in the email is associated with SPAM complaints. A block failure of URL Block may indicate one of several conditions.

  • You may use URLs too broadly, or the practices your affiliates may impact your reputation. We recommend you use distinct URLs for each type of mail, such as transactional and bulk. You should also investigate the underlying issue with the URL to verify it's not used in other email perceived as SPAM.

  • The recipient may not be actively engaged with your organization, as evident through no or low opens or clicks. Inactivity directly correlates to complaints. We recommend you attempt to engage inactive recipients with a separate reactivation mailing and purge non-respondents from your lists. To create this mailing, identify inactive recipients who have not opened or clicked in mailings over the past six months and then send those recipients messages over the next 30 days to remind them of the relationship and allowthem to opt out of future email. After the 30 day window,send recipients with no open or click activity one final "Sorry to see you go" message that allows them to opt in, and then remove them from mailing lists.

  • You may email the recipient too frequently or not frequently enough. If you email too frequently, the recipient may identify the email as SPAM. If you email too infrequently, the mailing may not cause the recipient to remember giving you permission to send to them. We recommend you review the frequency of your mailings and adjust it as necessary to be consistent with recipient expectations. You should also offer recipients a choice on both frequency and content and then verify recipients understand what they sign up to receive, including the frequency of when to expect email.

  • The email message may not target its recipients appropriately, or its content is not relevant to the recipient's preferences. We recommend you provide sample email for recipients to review during the sign-up process and allow them to update their profiles with information used to increase the content's relevance.

  • The recipient may not associate the email with your organization due to poor branding. We recommend you use consistent, prominent branding in the 'From' address, 'From' name, and subject line.

  • The recipient may not associate the email with permission granted to your organization, a third-party you use for list rental, or an affiliate program. We recommend you use explicit methods to obtain and disclose permissions, such as through a double opt-in feature. To remind recipients of why they receive messages, you should prominently display permission statements in the mailings to explain that recipients subscribed to the mailing list. You should also reconfirm the permission or track other indicators of sustained interest such as responses and donations. We recommend you also investigate permission practices of affiliates and send follow-up messages to recipients to confirm consent before you add third-party names in lists.

  • The recipient may assume the mailing is the same as a similar mailing they have already opted out of. We recommend you create email campaigns and newsletters around distinct topics to help recipients identify which they want. You should also properly design email and enewsletter templates to handle opt-outs for specific messages and campaigns in the proper hierarchy.

An email message may return a block failure if the email volume exceeds the limits or capacity of the recipient's mailbox provider.

To avoid returned or delayed messages, our system uses a process known as throttling to restrict the number of concurrent connections it makes with mailbox providers to comply with their threshold specifications. Our email specialists continually monitor throttling limits and adjust our send rates as necessary — or as required — to ensure email performance.

An email message may return a block failure because of a security policy violation. A block failure of Security Violation/Virus may indicate one of several conditions.

  • The recipient's mailbox provider may not be able to verify your organization's identifying information using authentication methods such as SPF or DKIM. For more information, see Sender Authentication

  • Your cumulative daily volume may exceed the number of emails allowed the limits set by smaller domains to protect servers from SPAM. We recommend you determine the percentage of the email blocked and importance of recipients at the domain. If necessary, distribute the volume over multiple days.

An email message may return a block failure if Unknown User hard bounce failures reach an unacceptably high level. A block failure of List Management may indicate one of several conditions.

  • Your mailing list may contain a high number of undeliverable records because it has not been mailed to recently or too much time as passed between the list capture and the mailing. This is one of the main reasons by some major mailbox providers block incoming email. We recommend you adjust your mail frequency for customer preference and value and review all segments of the list on a regular basis to ensure brand visibility, the continuity of communication, and address delivery. To reduce the likelihood of a complaint, set standards to send first communications within five to 10 days after data capture. If you're mailing to an "old" segment, deploy the mailing slowly to avoid spikes in Unknown User failures.

  • You may not adequately validate email addresses during data capture. We recommend you send follow-up email to new recipients to confirm opt-in permission and validate delivery to the address. If email bounces for reasons that indicate an invalid or inactive email account, remove the address and contact the recipient for new or updated email address information. To minimize typographical errors, we recommend you require double-entry of email addresses during online registration or opt-in. We also recommend you perform address hygiene to correct common misspellings on major domains before you add large quantities of addresses to your list and then send a confirmation email to corrected addresses.

  • For a high incidence of stale, inaccurate, or fictitious data, you may have unreliable data sources such as from a list rental or affiliate. We recommend you investigate the data compilation and management practices of your data sources and confirm consent and delivery before you add third-party names to a list. We also recommend you contact recipients for new or updated email address information and perform address hygiene to correct common misspellings on major domains before you add large quantities of addresses to your list, then end a confirmation email to corrected addresses.

An email message may return a block failure of Authentication if the recipient's mailbox provider can't verify your organization's identifying information using authentication methods such as SPF or DKIM. or more information, see Sender Authentication