An email domain is the part of an email address that comes after the @ symbol.
For example, when you send personal emails via Gmail, your domain is gmail.com. If you’re a business, your company likely has a designated domain that often matches the website address.
A domain reputation is the overall condition of a domain. To a great extent, it influences email deliverability — all emails you sent minus bounces and spam complaints. Domains with good history and reputation have a higher chance to have their emails delivered to subscribers’ inboxes instead of spam folders.
Conversely, senders with a bad domain reputation may even see their transactional emails end up in the spam folder.
The domain reputation along with the IP address reputation (the condition of the IP address) make up the sender’s overall reputation. Don’t assume that a new IP address will fix a damaged domain reputation. While the IP reputation can be reset with a new IP address, the domain reputation stays with you even when you change a device.
Mailbox providers (Gmail, Outlook, Yahoo, etc.) measure a domain reputation on a scale from bad to high. Points are added or deducted for each mailing.
The better your reputation is on the scale, the more email services trust emails coming from your domain and put them into inboxes. How exactly mailbox providers award points is unknown because they keep it secret for safety reasons.
There are obvious factors that influence reputation in a negative way. For example, senders without email authentication won’t shake a poor reputation off unless they get verified. Doing email blasts without special email software will also be no good for the sender’s reputation.
Other things that impact the domain reputation are less obvious and we talk about them next.
Whether you’ve just set up a new domain or been using one for a long time, there’s a list of practices to avoid to keep a domain reputation high. Since a domain reputation is hard to repair, it’s vital to avoid these things.
Mailbox providers know the look and feel of spam because they analyze literally (yes, literally) every email and see if it has anything in common with spam. Here are some of the most common red flags for mailbox providers:
Mailbox providers create blacklists to tackle spamming. Senders who get blacklisted can no longer reach inboxes which is a major blow to deliverability and a domain reputation.
Senders get blacklisted when too many recipients mark their emails as spam or junk. It may take just one email with too many complaints to blacklist the sender’s domain.
Spam traps are also called honeypots, only the honey isn’t sweet. A spam trap is an email address used exactly for the purpose of catching spammers. There are three types:
Hitting a spam trap is often the main reason for being blacklisted. Unlike spam complaints and bounce rates, spam traps are hard to identify. The best way to tackle them is to prevent them from getting into your database by using legal ways of building a contact list.
Mailbox providers are suspicious of sudden changes in senders’ behavior because inconsistent mailing is typical of spammers. That’s why legitimate email marketers plan their campaigns while spammers don’t care about reputation and only want instant results.
Here’s some inconsistent behavior that mailbox providers may consider suspicious:
Mailbox providers believe in natural growth. That’s why they don’t see it as normal when new domains start sending mass emails straight away.
According to their logic, senders with new domains can’t have many subscribers, and if they do, the contact list was bought. It takes time to build a domain reputation up to look legit in the eyes of mailbox providers.
Mailbox providers have analytical tools called postmasters. They analyze deliverability, spam complaints, IP and domain reputations. Gmail, Outlook, Yahoo — each popular mailbox provider has its postmaster.
One of the most popular postmasters is Google Postmaster Tools which analyzes emails sent into Gmail mailboxes. It ranks a domain reputation from bad to high:
Apart from Google’s Postmaster, you can consult these sources for checking your domain reputation:
Here are the best practices to keep your reputation high and avoid potential pitfalls.
A double opt-in is the process of getting an extra confirmation of an email address from a subscriber.
This extra measure assures the quality of a contact list. If a subscriber is willing to confirm an email address, he or she is genuinely interested in hearing from you.
The alternative is a single opt-in but this is the quantity vs quality debate. Single opt-in advocates argue that it’s a faster way to grow a contact list. Sure enough, but there are dangers associated with it: fake accounts, spam traps and misspelled email addresses end up on a contact list with a single opt-in.
That’s why a double opt-in is a more secure approach. This makes sure your contact list is legit and it’s pretty much impossible for spam traps and misspelled addresses to get in.
No one likes to lose subscribers but an unhappy subscriber is a potential source of trouble for your domain reputation. If people no longer want to hear from you — fair enough, give them a clear way to unsubscribe.
Obfuscating the unsubscribe link can only anger a subscriber. No one’s going to study an unwanted email for the unsubscribe link when it’s easier to send it straight to spam.
Unsubscribe links are usually placed in an email footer. The button doesn’t have to be large like a big banner — just visible enough and clickable.
Unsubscribing benefits both the recipient and the sender. The recipient no longer receives irrelevant content and the sender doesn’t waste time on uninterested subscribers who undermine the deliverability and reputation.
Emails with spam words in the subject line risk not reaching customers’ inboxes because mailbox providers see them as suspicious. Here are some examples:
Even if such an email slips through a spam filter and lands in an inbox, the recipient may not be baited into opening it. If the recipient opens it and doesn’t like the clickbaity look of it, the email has a good chance of going to the spam folder. Either way, it’s a blow to the sender.
List hygiene has a direct impact on your deliverability and domain reputation.
You may use a double opt-in and be sure your contact list is full of top-quality subscribers but if they stop reading you, they’re as useful as fake jeans pockets. In fact, inactive contacts may be abandoned addresses — time bombs set to turn into spam traps. By regularly cleaning your list up you remove inactive contacts and thus increase deliverability.
How regular should clean-ups be? It depends on the volume and frequency of your mailing. If you send emails every day or almost every day (e.g. newsletters), look with suspicion at contacts that don’t react to you for a couple of weeks. If you send just a couple of emails per month, this period can be longer.
We recommend clean-ups every 2 to 6 months to maintain list hygiene, keep deliverability high and protect domain reputation.
Use analytics provided by your ESP of choice to track engagement rates through stats like open rate, bounce rate and spam complaints. This will help you see if subscribers find your content engaging and if there are any problems with deliverability.
Meanwhile, tools like Google’s Postmaster will give you a detailed overview of how your domain and IP address perform.
By making the most of available resources, you’ll get the best look at your email marketing performance, including your domain reputation.
A blacklist is a list of IP addresses and domains suspected of sending spam. Even if you’re convinced that you only send high-quality content, this alone isn’t enough to stay clear of blacklists.
Tools like MXToolbox or Mailtester will help you see if your domain is listed on any popular blacklist.
To minimize the risk of getting blacklisted you need to combine the best practices listed above: a double opt-in, list hygiene, an easy-to-see unsubscribe link, and overall good quality of your content.
Email authentication is needed to verify the authenticity of the sender. Mailbox providers require it to make sure the sender is not a spammer.
Verified senders enjoy two benefits:
Email authentication includes three protocols: SPF, DKIM and DMARC.
Set up authentication in your ESP of choice. You can do it by yourself in Selzy’s personal account or have it done for you by ordering the service — just contact us through the chat for help.
Mailbox providers are suspicious of emails from new domains and IP addresses because every new address is a potential spam threat. Under a bit of suspicion, an email goes to the spam folder.
To look legitimate to mailbox providers, it’s important to create a domain reputation by warming a domain up. The logic is simple: mailbox providers believe in natural growth and to them, new domains can’t have many contacts.
A warm-up is a gradual process. At the start, you send a few emails to a small audience. For example, transactional emails only. As time goes by, your audience and email frequency grow.
The warm-up can take up to two months. Old domains usually don’t need it, especially if the sender sticks to a consistent schedule.
| Week | Number of recipients | % of contact list |
| 1 | 2,500 | 5% |
| 2 | 5,000 | 10% |
| 3 | 10,000 | 20% |
| 4 | 15,000 | 30% |
| 5 | 25,000 | 50% |
| 6 | 35,000 | 70% |
| 7 | 40,000 | 90% |
| 8 | 50,000 | 100% |
What a warm-up schedule may look like
A subdomain is related to your domain but mailbox providers treat it separately. That’s a great solution when you want to prevent different email types from affecting each other.
If one of your subdomains receives spam complaints or gets blacklisted, it’s less likely to impact your main domain than if you used one domain for all email activities.
Subdomains are often used in transactional emails. No one wants emails like payment confirmation or password reset to land in the spam folder, that’s why it’s practical to separate them from the rest.
Some use a subdomain for sending promotional emails to save the root domain from potential trouble. If a promotional email receives many spam complaints it won’t affect the main domain.
An email domain reputation is the overall condition of your domain. It’s one of the factors making up the overall sender’s reputation.
It’s a crucial factor to deliverability: good reputation = higher chance of good deliverability. For senders with a bad domain reputation, even transactional emails will go to the spam folder.
You can track the domain reputation with postmaster tools, for example, Google Postmasters Tools. Points are added or subtracted for every mailing.
A number of factors negatively impact the domain reputation. To prevent it from happening, rely on proven solutions listed in this table.
| ❌ Threats to domain reputation | ✅ Solutions |
| Poor emailing practices | Higher content quality
Easy unsubscription Regular stat checks No spam words in the subject line |
| Getting blacklisted | Email authentication
Regular email list clean-up Use of subdomains |
| Spam traps | Double opt-in |
| Volume inconsistency | Planning campaigns ahead |
| Too many emails from a new domain | Domain warm-up |
