Trend Micro

Trend Micro is a spam filter, block list, and firewall solution for businesses. Mail is routed through mailservers owned by Trend Micro (example: *.trendmicro.com). The recipient is able to manage a lot of delivery settings such a allow lists, so it helps to ask the recipient to run the described debugging tests in the user guide to identify and resolve delivery issues.

Codes

550 · 554

550↑

550 5.7.1 <example@example.com>: Recipient address rejected: ERS-Customized-Block.

'ERS' stands for Trend Micro's 'Email Reputation System', which provides custom levels of threat protection including sensitivity preferences and custom filters.

• https://success.trendmicro.com/solution/TP000087438-How-do-I-edit-Reputation-Settings

554↑

554 5.7.1 <example@example.com>: Recipient address rejected: BLOCK-SEND-ER.

There's certain criteria in the message itself that this recipient is blocking, which could include a block on the sender's domain/IP by an admin of the recipient's domain.

• https://success.trendmicro.com/solution/1055758-blocking-an-email-address-or-domain-in-hosted-email-security-hes#collapseTwo

554 5.7.1 <example@example.com>: Recipient address rejected: Invalid-Recipient.

554 5.7.1 <example@example.com>: Recipient address rejected: NO-DOMAIN.

The recipient is permanently undeliverable unless manual changes are made on the recipient's end to allow the sender's domain and/or sending IP. This doesn't necessarily mean the message was purposefully blocked, just that routing of the message through Trend Micro is not yet allowed.

• https://success.trendmicro.com/solution/1120618-send-outbound-mails-to-trend-micro-email-security-tmems-failed-with-554-return-code

554 5.7.1 <example@example.com>: Recipient address rejected: BLOCK-RCPT.