How does TLS inbound affect email deliverability and sender confidence?
Summary
What email marketers say9Marketer opinions
Email marketer from Email Marketing Forum posits that while TLS itself might not be a direct factor in spam filtering, the lack of it could raise flags with some email providers. They state that using TLS contributes to a more secure setup, which could indirectly help with deliverability.
Email marketer from Reddit suggests that a broken TLS connection can make recipients wary of your emails and decrease confidence in the sender. It can also affect email deliverability because of Google's push to encrypt everything.
Email marketer from SendPulse indicates that enabling TLS encryption helps protect email content during transmission. It implies that using TLS contributes to maintaining a secure email environment, which can positively influence sender reputation and deliverability rates, but this is indirect.
Email marketer from Stack Overflow shares that while TLS encrypts email in transit, some servers may not support it, leading to fallback to unencrypted connections. Suggests checking if server supports STARTTLS.
Email marketer from StackExchange explains that using TLS helps protect the privacy and integrity of email communications. States that email servers may lower spam scores when detecting TLS and that while it's not a guarantee, not using it will reduce the deliverability.
Email marketer from Email Geeks shares that it might not directly affect deliverability but they think it decreases confidence in the sender. When some people see that Gmail broken lock warning it makes them a little wary and, rightfully so, especially if it keeps happening. In addition to intangibles there are concrete security benefits to TLS.
Email marketer from Mailgun explains that TLS (Transport Layer Security) is a protocol that encrypts email communications, protecting them from eavesdropping and tampering. Using TLS enhances email security and sender reputation, which can indirectly improve deliverability.
Marketer from Email Geeks suggests to tell Google their TLS is broken but come with evidence. They also mention that if having trouble establishing the session using TLS, could be any number of things (including a flaky network), but the error logs would hopefully be able to help more.
Email marketer from Email Security Blog shares how to implement DANE and MTA-STS to improve email security. States that while TLS encrypts emails in transit, DANE validates the endpoint via DNSSEC and MTA-STS does this via CA mechanisms for opportunistic TLS. Also states that if a session cannot be negotiated, email will be sent in clear text.
What the experts say3Expert opinions
Expert from Spam Resource explains that STARTTLS offers opportunistic encryption, which means it attempts to upgrade an unencrypted connection to a TLS-encrypted connection. They also state that if encryption is not negotiated, the session will continue unencrypted. They do not believe the lack of opportunistic TLS negatively effects delivery.
Expert from Email Geeks shares that TLS doesn't matter that much in terms of deliverability, as Google accepts mail that is not coming over a TLS encrypted channel. However, she states that the issue is a technical problem with the SMTP session, and the folks who own the SMTP server are responsible for it.
Expert from Spam Resource explains that Email encryption is an important tool to protect sensitive email content from unwanted exposure. States that the most common usage of email encryption is over the transport layer (TLS), encrypting the communications pathway while the email is in transit.
What the documentation says3Technical articles
Documentation from RFC Editor defines Opportunistic TLS as encrypting email communications if the receiving server supports TLS, but still delivering the email unencrypted if TLS is unavailable. It acknowledges the risk of downgrade attacks but prioritizes widespread email delivery.
Documentation from Google answers that TLS encryption helps secure email communication. While Google doesn't explicitly state it directly impacts deliverability, ensuring TLS is enabled for connections to Google helps protect sensitive data, potentially improving sender reputation and confidence.
Documentation from Microsoft shares TLS settings when configuring SMTP to send emails. It highlights the importance of using secure connections and specifies different TLS settings and versions for improved security.