Email deliverability is how reliably your emails reach your recipients' inbox instead of being filtered into spam. This matters any time you send email from your own domain — whether that's day-to-day business emails or a bulk campaign. Follow the practices below and you'll lower the chances of your emails getting flagged as spam or blocked outright.
Use a recognizable sender name
Send your emails from an address that includes your name alongside your brand name, for example "Priya at Acme Design" rather than "noreply@acmedesign.com." Recipients scan a crowded inbox quickly, and they're more likely to open an email that looks like it came from a real person.
| alert-success | A sender name like "Priya from Acme Design" performs better than a generic one like "Acme Design Team," because it signals a real person is writing to them. |
Avoid spam-trigger content
When an email provider receives your message, it scans the content for patterns that are typically associated with spam. Avoiding these patterns makes it much more likely your email passes straight through to the inbox.
Formatting and wording to avoid
Writing in all capital letters
Using more than one or two exclamation points in a row
Red font or other attention-grabbing colors
Spam-associated words and phrases, such as "free," "cheap," "pre-approved," "$$$," "urgent," or "don't wait!"
Broken HTML in the email body
If you avoid these, you'll clear this check easily in most cases. The next section explains the other major factor: your domain reputation.
Protect your domain reputation
| alert-warning | If your domain ends up on a blacklist (a list of domains that email and security providers treat as unsafe), it can take weeks to be removed, and your emails may be blocked or sent straight to spam for everyone on your list in the meantime. Prevention is far easier than recovery. |
What is domain reputation?
Domain reputation is how trustworthy your sending domain (the part of your email address after the @ symbol) looks to email providers, based on how your past emails have performed. A domain with a poor reputation is more likely to have its emails sent to spam, even if the technical setup is otherwise correct.
The reputation of your IP address still plays a role, but it's no longer the only factor providers look at. It's possible to send from an IP address with a good reputation and still land in spam, because of a poor domain reputation.
How to keep your domain reputation strong
Scan your website regularly for malware, since an infected site is one of the most common reasons domains get blacklisted
Keep your website's software and operating system up to date
Act quickly if you notice warning signs, such as a drop in email opens or reports of your links being blocked
Write clear, compelling subject lines
Keep your subject line between 30 and 50 characters, including spaces. Email apps and mobile devices often cut off anything longer, so anything past that length may never be seen. Your subject line should give readers a clear, honest idea of what's inside the email.
Avoid the following in your subject lines:
Spam-associated words, such as "urgent," "buy now," "win," or "free"
Writing the whole subject line in capital letters
Spelling mistakes
Overusing emojis
Subject lines that don't match what's actually in the email — this leads people to unsubscribe and lose trust in your brand
Get clear consent before you email people
Consent means someone has clearly agreed to receive email from you. Best practice is to be specific about what they're signing up for, and to make it easy for them to opt out (unsubscribe) at any time.
Check your blacklist status
If your IP address or domain has a poor reputation, your emails are more likely to land in spam. You can check your current status using a free lookup tool, such as MXToolbox or Multirbl.Valli.
In the tool, enter your domain name or IP address
Click Check (or the tool's equivalent button)
Review the results — the tool will tell you which, if any, blacklists you appear on
Polish your email before you send
Keep fonts and colors simple
Stick to one font and a consistent size throughout your email. Irregular fonts, sizes, and colors make an email look untrustworthy to recipients, and can also trigger spam filters. This includes invisible text, such as white font on a white background, which spam filters treat as a red flag.
Check spelling and grammar
Proofread every email before sending. Spelling and grammar mistakes make your email look unprofessional and are also one of the patterns spam filters watch for. Read your email aloud once before sending as a final check.
How you'll know it's working
There's no single setting that guarantees your emails will never reach spam — deliverability depends on the combination of practices above, applied consistently over time. You'll know your efforts are paying off when you see:
A steady or improving open rate for your emails
Few or no reports from recipients that your emails are landing in spam
A clean result when you check your domain and IP against blacklist lookup tools
Troubleshooting common deliverability problems
Problem: My emails are landing in recipients' spam folders
Cause: This is usually a combination of a weak domain or IP reputation and content that trips spam filters, such as spammy wording, broken HTML, or irregular fonts and colors.
Fix: Review your recent emails against the Avoid spam-trigger content section above, and check your domain against a blacklist lookup tool.
Problem: My domain or IP address shows up on a blacklist
Cause: This is most often caused by malware on your website, a sudden spike in emails sent, or a high number of spam complaints from recipients.
Fix: Scan your website for malware and resolve any issues you find. Once your site is clean, most blacklist providers offer a delisting request form — submit one for each list you appear on. Removal can take anywhere from a few days to a few weeks.
Problem: My open rates are dropping over time
Cause: This often means recipients no longer want your emails, which signals a poor sender reputation to email providers over time.
Fix: Remove inactive or unengaged contacts from your list, and make sure everyone on it gave clear consent to receive your emails — see Get clear consent before you email people above.