Common Email Deliverability Hurdles

Spam

Email spam, also known as junk email, is unsolicited messages sent in bulk by email. Most Internet Service Providers (ISPs) filter out spam from their users’ inboxes. More than 300 companies offer spam filtering services, although their filter logic varies. The most common spam filters are based on keywords or email content. Others use email volume, customer complaints, or blocklists in their filtering logic.

Blocklists

Several high priority blocklists use a spamtrap or “honeypot” email address to identify spammers. The owner reserves these addresses and doesn’t use them to receive email. Any email sent to these reserved addresses is identified as spam. The blocklist owners plant these email addresses in various lists that can be purchased for sending mass unsolicited email. That’s why it’s important to never use purchased email lists. Only send email when you have obtained consent from the recipient to do so.

Salesforce monitors the IPs we use to send mail to ensure that they aren’t on the high priority blocklists. On the rare occasion that one of our IPs ends up on a major blocklist, we work as quickly as possible to identify the cause. We then work with the blocklist owner to clear the entry and with the customer that caused the issue. Usually, the cause of the issue is an accident or misunderstanding rather than a malicious action. Sometimes, we must remove an organization's ability to send mail while we work with them to clean up the issues that led to the blocklisting.

Feedback Loops

Some email services provide the user with the option to flag email as spam. This action registers a complaint that some mailbox providers collect so they can provide visibility back to the senders. The sender can then remove the recipient from the specific campaign or database.

Salesforce collects this feedback loop data but doesn’t currently make it available to our customers.

Allowlists

Salesforce sends email from a growing list of IP addresses. If your organization blocks any of these IP addresses, it can prevent users from receiving all emails sent from Salesforce.

We recommend that you avoid IP allowlists whenever possible and instead rely more on standard email security protocols (such as SPF, DKIM, and DMARC) to determine acceptance of email. For customers using Email Relay, we recommend that you use the standard email security mechanisms instead of restricting your relay to the Salesforce IPs.

If you must use an allowlist, then we recommend that you include all the Salesforce addresses used to send email. And don’t forget to regularly update your allowlist with changes published in the latest “Salesforce IP Addresses and Domains to Allow” knowledge article.