What causes a Symantec email block and how to fix it?

Marketer from Email Geeks suggests if you're not trying to send email through them then it's a local site misconfiguration.

Email marketer from Email Geeks Forum shares that if you're using a new IP address, gradually warm it up by sending email to engaged subscribers first. Avoid sending large volumes of email to unengaged subscribers, as this can damage your IP reputation and lead to blocks.

Email marketer from Email Geeks Forum explains that regularly cleaning your email list to remove inactive or problematic addresses is important. Sending email to a large number of inactive addresses can increase your bounce rate and lead to deliverability issues.

Email marketer from Email Deliverability Forum explains that implementing DKIM (DomainKeys Identified Mail) helps verify the authenticity of your emails. DKIM adds a digital signature to your emails, which allows receiving mail servers to verify that the email was sent from an authorized source and hasn't been tampered with.

Email marketer from Email Marketing Forum suggests that a poor IP reputation is a common cause of email blocks. Regularly check your IP address against blacklists and take steps to improve your sender reputation by sending consistent, high-quality email and adhering to email best practices.

Email marketer from Email Deliverability Forum shares that setting up feedback loops with major ISPs, including Symantec, to receive reports about spam complaints from your subscribers and use this information to identify and address issues with your email program is a solution.

Email marketer from Email Marketing Forum suggests that implementing a double opt-in process for new subscribers helps ensure that only legitimate subscribers are added to your list. Double opt-in requires subscribers to confirm their subscription by clicking a link in a confirmation email.

Email marketer from StackExchange explains that it is important to set up an SPF (Sender Policy Framework) record for your domain. This record specifies which mail servers are authorized to send email on behalf of your domain, and it helps prevent spoofing and improves email deliverability. Symantec uses SPF to help identify legitimate senders.

Marketer from Email Geeks shares that MX weight (aka "priority") means nothing at all in the real world, it is just a nice idea honoured by some and ignored by most.

Email marketer from Reddit shares that ensuring your sending server has a valid reverse DNS (PTR) record can help prevent being blocked. Many email systems, including Symantec, use reverse DNS to verify the legitimacy of the sending server.

Expert from Word to the Wise details that improving sender reputation involves sending consistent, high-quality email, adhering to email authentication standards, monitoring bounce rates and spam complaints, and promptly addressing any issues that arise. Engaging with feedback loops can also provide valuable insights.

Expert from Word to the Wise explains that Symantec blocks can be caused by various reasons, including poor IP reputation, lack of proper authentication (SPF, DKIM, DMARC), high spam complaint rates, or triggering Symantec's content filters. Reviewing bounce messages or working with Symantec support can provide more specific details.

Expert from Email Geeks explains that legitimate mailservers will send mail to the MX record with the lowest number, or if that fails the next lowest, and only if that fails to the highest. High preference MXes are (or used to be) backup MXes, often off-site, often run by other people ... which means often with much vaguer spam filters. So spammers (used to) send to the high preference MXes to avoid spam filters. So that's a good place to put tarpits or honeypots.

Documentation from Broadcom Support details that to resolve relay errors, ensure that the sending server is properly authenticated, the sender's IP address is whitelisted in the Symantec Messaging Gateway's relay settings, or the SMTP settings are correctly configured to use authentication if required by the gateway.

Documentation from Symantec Support explains that using message audit logs to look at more details of the reason for rejection will help. These often contain a verbose reason for the block.

Documentation from DMARC.org details that implementing a DMARC policy to provide instructions to receiving mail servers on how to handle emails that fail SPF or DKIM checks is important. A DMARC policy can instruct mail servers to reject, quarantine, or accept emails that fail authentication checks.

Documentation from Symantec Support explains that the error message "553 you are trying to use me as a relay" indicates that the sending server is not authorized to relay email through the Symantec Messaging Gateway. This can occur due to incorrect SMTP settings or the sender's IP address not being permitted to relay.