Deliverability

Deliverability is the term used by email marketers to define the success, or lack of success, of getting messages delivered into the inbox of subscribers rather than being blocked or sent to the spam/junk folder. Understanding deliverability is critical to the success of email marketing campaigns. The more messages delivered to the inbox, the better your opportunity for return on investment will be. However, more isn't always better. A high open/view percentage for a modest size list looks better to inboxes than a lower open/view rate sent to a much larger audience. This document covers the most critical factors, in detail. However, readers should keep in mind that the email marketing landscape is constantly shifting. The rules are subject to change at any time.

Sender Reputation

The most critical aspect in terms of getting you into the inbox is your sender reputation. Damage to your reputation can cause you to be throttled, bounced, blocked, or have your emails go missing. Mailbox providers such as Gmail, Yahoo!, and Outlook track your sending reputation and keep an eye on how your emails do in the inbox. Reputation factors that can affect deliverability include:
 

• Complaint Rates
  • Many email providers have extremely low thresholds for spam complaints when it comes to bulk email sending. In 2024, both Gmail and Yahoo! instituted strict policies for spam complaints in bulk sends. They expect spam rates to be regularly no higher than .1% and may begin penalizing you when your rate exceeds .3%. That means on a send of 10,000 address only 30 spam complaints could cause you to be categorized as a spammer.
     
• Bounce Rates
  • Some bouncing in an email is normal. What you want to avoid is consistently higher than normal bouncing and spikes of extremely high bouncing, either of which may make you appear suspicious to inbox providers. The most avoidable types of bouncing are hard bounces which occur when sending to email addresses that do not exist (either because you have misspelled the email address or the email address has been deactivated). emfluence automatically holds all emails that hard bounce preventing you from sending to them again. Sending on a regular cadence to your list will allow old addresses to bounce and be taken off your list naturally. Since a third of an email list can turn over during the course of a single year, if you have sections of your list are only mailed a few times a year you are more likely to see spikes in bouncing. For sends to 500 or more, your bounce rate should never exceed 10% of the list sent to. However, just because your overall rate may be under that threshold that doesn't mean your rate wasn't higher at certain domains.
  • Unknown Users: The term unknown users refers to email addresses that have been abandoned or shut down by the email provider and also incorrect or misspelled addresses. A large percentage of these addresses on a send can adversely affect the rest of your list causing good addresses to be bounced.
     
• Unsubscribe Rates
  • Because you should only ever be starting with a list of recipients who know your brand and have opted in to receive your emails, your unsubscribe rate on any given email should be relatively small. It's always better for someone to unsubscribe rather than complain, but high unsubscribe rates can still affect your deliverability. Domains like Yahoo! or Gmail who notice several of their users unsubscribing from your emails over short periods may decide to move you to the spam folder or possibly throttle or block deliverability of your emails. For sends over 500 recipients, we expect our clients to stay under a 1% threshold. For smaller sends that number drops down to .5%
     
• Spam Trap Hits
  • Spam traps are inboxes set aside to find and hurt the reputation of spammers and those with poor list hygiene. These may pristine, recycled, or typo traps.
    • Pristine Traps are email addresses that are published on public web sites, but hidden so a normal user would never see them. Pristine Traps end up on a list usually from questionable processes, like scraping the web for everything that looks like an email address or through an unverified purchased list by a provider that came across the address by questionable means. These email addresses were created as spam traps and were never real email addresses.
    • Recycled Traps are email addresses that were used by real people in the past, became abandoned, and at some point were converted into a trap by the inbox provider. Regular sending behavior will see those addresses hard bounce off your list prior to becoming traps. After a period of time, domains like Yahoo!, Gmail, Microsoft and others will reactivate a handful of inactive accounts. Once reactivated, they won’t return a hard bounce anymore but are now an active spam trap that marks everyone sending email to it as a misbehaving sender.
    • Typo Traps are email addresses with common misspelled domains (ex: gmial.com). Typo spam traps are used by mailbox providers and blocklist providers to identify senders with poor list acquisition and list hygiene practices. 
       
• Blocklists
  • Public email blocklists are lists of IP addresses and domains that have been reported and listed for malicious activity including spam, malware, phishing, and DDoS attacks. These are published and made available. Systems that use a blocklist will match incoming email off of a listed domain or IP and block all traffic. emfluence monitors its IPs through Validity to be aware if any of its IPs ever show up on a list. Some lists will allow you to manually request removal. However, some will not. The best way to avoid having to deal with a blocklist is to never get on one.

Authentication

• When sending through emfluence as your own domain, authentication is a necessary step to confirm your identity to the end recipient. Authentication is done through a series of records added to your domain's DNS (usually this occurs during the client setup phase, unless a domain needs to be added at a later date).
  • DKIM: DKIM works through a digital signature that’s attached to the header of each email sent from the emfluence Marketing Platform. The receiving system can verify the signature by looking up the sender's public key published in a DNS record. A valid signature guarantees the sender has permission to send email on behalf of your domain and that the email has not been modified since the signature was added. Settings for DKIM records needed in emfluence can be found here.
  • SPF: As SPF looks back at the email mail server responsible for the domain, rather than the individual from address, SPF is covered by emfluence automatically.
  • DMARC: While not necessary to send through emfluence, DMARC may be necessary for your emails to get to your recipients. DMARC is an authentication protocol that works on top of SPF and/or DKIM records. More and more inboxes are requiring DMARC records. Yahoo! and Gmail both began requiring it for bulk senders in 2024. For emails sent through emfluence, if you have a valid DMARC record and you are passing DKIM, DMARC should also pass in most instances. Learn more about setting up DMARC here.

emfluence will display authentication status in multiple places within the platform, including in the Options menu under Account Settings > Sending Domains and in Pre-Flight tests. If you notice your domain is not passing, you should reach out to support@emfluence.com. NOTE: If you have an older account still using the "emfluence" DKIM keys rather than the current standard "emfluence-k1" and "emfluence-k2" keys you will not be shown as passing. We suggest all clients update their DKIM entries to the current method.
 

Email Content

• Subject Line
  • Make sure the subject line is on point with your messaging. Avoid using words or phrase in your subject and content that may trigger spam filters. Some spam filters will see words and phrases that repeat as potentially spammy, attempt to modify content when applicable.
     
• From Name & From Address
  • Consistently send from the same addresses when possible. You may suggest your recipients save that address in their address book/safe sender list. If you plan to change that address let them know beforehand so they are on the lookout for emails coming from a different address.
  • Make sure your domain matches your sending name. If you have multiple brands, and multiple domains, set up in emfluence, make sure you are using the proper combination for a send.
  • Have a valid sending from and/or reply address. in 2025 Microsoft began enforcing that all bulk sends need to be sent from, or have a reply to address, that can be sent a response. Failure to do so may result in emails not being delivered.
  • Avoid sends where the ratio of images to content is too heavy.
  • Watch the size of your email and avoid emails where emfluence warns you the size may impact deliverability.
     
• Content isn't as large an issue with deliverability as it once was compared to overall reputation, but suspicious content can still help trigger spam warnings. Use common sense and try to avoid questionable words and phrases that might come off as potentially spammy to a filter. Also, some filters will ding senders for overusing repeated phrases which may also make your email look like spam.
   

List Hygiene and Sending Practices
 

• Never use an unverified purchased list through emfluence.
   
• Avoid link URL shorteners which have become taboo in many inboxes because of their overuse by spammers. Link shorteners may also interfere with emfluence's ability properly redirect and to track email links. Consider the amount of links in your email and always make sure you are using a full secure URL (which should begin with https://).
   
• As contacts bounce (either through a single hard bounce or through a number of repeated consecutive soft bounces), they will be held. As contacts unsubscribe, they will be suppressed. emfluence suggests not deleting these contacts. When contacts are deleted, their records are anonymized and anything about the record is forgotten. This means, if the addresses are ever re-added to the platform, they would be new available addresses.
   
• Cleanse large new imports, along with older lists you haven't sent to in a long time, and consider cleansing your full list on a yearly, bi-yearly, or quarterly timeline. Known bad addresses will be held automatically, but look through your Low category to see if some of those should be held as well. Learn more about list cleanses here.
   
• When using emfluence forms, or third-party forms, include a reCAPTCHA to help prevent bot-entries from making it into your account.
   
• When composing emails within emfluence, on the Preview step, use Proofs and Pre-Flight to test your messages.
   
• Send regularly and set expectations to your subscribers about how often they will hear from you. Mail providers and spam filters favor both established history and consistent sending. Sending infrequently, especially if you are on your own dedicated IP, may hurt your deliverability. Conversely, sending too often may cause some contacts to opt-out through unsubscribing or making a spam complaint.
   
• Be consistent across all channels as much as possible. Use a consistent sending address (you may also suggest your contacts add it to their safe sender's list). If you are sending from a separate domain or subdomain in emfluence than in Outlook, you may find some contacts (and even some email providers) begin treat them differently (especially if one has a far longer, or better, sending reputation than the other). While there are reasons for doing so, the practice of sending from a different domain may make it harder to balance keeping a strong reputation for each.
   
• Try not to overpower your emails with too much image versus text content. Consider the length of your email and consider optimizing images to keep the overall size down on larger sends such as newsletters. A reasonable size and a balanced text-to-HTML ratio will help with delivery. Keep an eye out for warnings of the size of your email which you can find beginning on the Preview step under the email Summary.
   
• Take a hard look at your engagement. The larger the percentage of unengaged contacts you have at a domain the more likely that domain may view you as a potential spammer. Having 250 engaged contacts out of 500 is far better than have 300 engaged contacts out of 5,000. 
   
• If you believe you may be having deliverability issues, send a copy of a recent send to the Seed List. Controlled through Validity, the seed list has addresses in several different inboxes that will test whether your email is going to the inbox, the spam folder, or missing (meaning it doesn't arrive) at the various providers. You won't have direct access to the seed list results, but emfluence can check those for you (remember to let us know if you are going to send to the seed list). Reporting data may be a day or two behind. If you don't have access to the seed list, or haven't sent to it in some time, check with emfluence to get the newest version (sending to old/retired seeds may skew your results)
   
• If you are seeing high complaint rates, consider scaling back your sends, sending a repermission campaign, and moving an unsubscribe link to the top of your email. While high unsubscribe rates aren't good, a higher unsubscribe rate is far better than a high complaint rate.