Why are my emails to Gmail corporate addresses bouncing with RFC 5322 compliance errors?

Email marketer from Mailjet explains that RFC compliance errors can occur if the email's 'From' header is missing or incorrectly formatted, if there are issues with the message's MIME structure, or if the email contains invalid characters or formatting in the headers.

Email marketer from Stack Overflow responds that missing 'From:' header may cause this error, it is required. You can set it with `$headers .= "From: info@example.com";`.

Email marketer from Reddit notes that issues might not be with the format alone, but the content as well. Spam filters have gotten pretty sophisticated about the actual text/links in your emails. Gmail is cracking down.

Email marketer from SparkPost shares that correctly implementing DKIM and SPF records can significantly reduce the likelihood of emails bouncing due to RFC 5322 compliance errors, as it confirms that the email is genuinely sent from the claimed domain.

Email marketer from Litmus shares that implementing SPF, DKIM, and DMARC records can help authenticate your emails and improve deliverability to Gmail corporate addresses, reducing the likelihood of RFC 5322 compliance errors. Not doing so is like sending mail without a return address.

Email marketer from Sendinblue mentions that improper HTML coding or the inclusion of invalid characters in the email's headers or body can cause RFC 5322 compliance errors. Clean and valid code helps ensure proper email formatting and delivery.

Email marketer from Email on Acid states that issues related to header folding (when long header lines are split incorrectly) can trigger RFC 5322 compliance errors. Ensure proper formatting and line breaks in email headers to avoid these issues.

Email marketer from Reddit discusses the importance of configuring a PTR record to point from your sending IP address to your domain. This helps to verify your server's identity and improve deliverability to Gmail corporate addresses, reducing RFC 5322 errors.

Email marketer from GMass shares that avoiding spam triggers such as using URL shorteners, excessive exclamation points, or certain keywords can help improve email deliverability to Gmail corporate addresses and reduce the chances of RFC 5322 compliance-related bounces.

Expert from Email Geeks mentions the absence of a Message-ID which is not ideal, but shouldn't cause the error. A reasonable smarthost should add a Message-ID if needed.

Expert from Spamresource explains that the 'From' address needs to be formatted correctly and exist. It must not contain invalid characters, and the domain part of the address must resolve to a valid DNS record. Check that the email is using a valid return-path and that there are no encoding issues with the address.

Expert from Email Geeks explains that the EHLO is not a fully qualified domain name and also notes the inclusion of a Russian language link to go.microsoft.com is unusual.

Expert from Word to the Wise explains the importance of properly implementing the List-Unsubscribe header. A missing or incorrectly formatted List-Unsubscribe header can lead to increased spam complaints and potential deliverability issues, which may indirectly contribute to RFC 5322 related problems as ISPs become more scrutinizing.

Expert from Email Geeks points out that the email is being sent over IPv6, which has extra requirements. She recommends full circle rDNS setup (IP -> hostname -> IP) and ensuring the hostname doesn't have an AAAA record, with the forward DNS entry pointing to the sending IP.

Expert from Email Geeks states the email is missing a From: header.

Expert from Spamresource shares that issues with the email headers, such as missing required headers or incorrectly formatted headers, can cause RFC 5322 compliance errors. Ensure that all headers adhere to the specifications outlined in RFC 5322 to avoid these issues.

Expert from Email Geeks notes some funky header folding and suggests checking for large numbers of email addresses in the To: header or any unescaped/poorly escaped non-ASCII characters, which could cause long headers.

Expert from Email Geeks references the Google support link's advice: Web links in the message body should be visible and easy to understand, ensuring recipients know what to expect when clicking.

Documentation from Google Workspace Admin Help explains that RFC 5322 compliance errors arise when emails don't adhere to the Internet Message Format standard, specifically the 'From' header, which must be present and correctly formatted to ensure proper email delivery to Gmail.

Documentation from Microsoft Support details that incorrect or missing settings within Microsoft Exchange Server can lead to RFC 5322 compliance issues. Ensure that the 'From' header is properly configured and that the server's SMTP settings adhere to email standards to avoid bounces.

Documentation from RFC Editor details that RFC 5322 defines the Internet Message Format, specifying the structure and syntax of email messages. The 'From' header is a mandatory field, and any deviation from the RFC's specifications can result in compliance errors and email delivery issues.

Documentation from IETF explains that RFC 2822 (superseded by RFC 5322, but relevant for historical context) defines the standard for the format of ARPA Internet text messages. Non-compliance with these standards can cause delivery issues.

Documentation from Amazon Web Services highlights that configuring Amazon SES (Simple Email Service) properly is crucial for ensuring emails comply with RFC 5322 standards. Check your SES settings, including authentication, sender verification, and feedback loops, to prevent deliverability issues with Gmail.