IP reputation refers to a trust score that email providers assign to an IP address, which reflects its historical sending practices and behaviors. IP reputation is volatile; it can reset quickly when infrastructure or routing changes.
Reports of spam or sudden changes in sending patterns can negatively impact an IP’s reputation. However, email providers have shifted their approach and no longer rely primarily on IP data for general filtering decisions. Instead, they now focus on IP reputation to help reduce the risk of exposing their users to potentially harmful servers.<\/p>\n\n\n\n
Shared vs. Dedicated IP reputation<\/strong><\/h2>\n\n\n\n\n- Dedicated IP<\/strong>: exclusively yours. This means you\u2019re in full control of your sender reputation which can help your emails reach inboxes more reliably.<\/li>\n\n\n\n
- Shared IP<\/strong>: used by multiple senders. This means that your email reputation is affected by other organizations in the pool and even if you\u2019re doing everything right your email delivery can be affected.
<\/li>\n<\/ul>\n\n\n\nHow is your IP reputation score calculated?<\/strong><\/h2>\n\n\n\nMultiple factors can impact your IP reputation score. Key factors include:<\/p>\n\n\n\n
\n- Spam Complaints<\/strong>
Recipients flag an email as spam; high complaint rates significantly impact IP reputation.<\/li>\n\n\n\n- Bounce Rates<\/strong>
<\/strong>High percentages of hard or soft bounces indicate list issues. Soft bounces occur if inboxes are temporarily full; hard bounces occur for invalid or non-existent addresses.<\/li>\n\n\n\n- Blacklist listings<\/strong>
<\/strong>Inclusion in spam or threat databases (e.g Spamhaus) severely damages the IP reputation.<\/li>\n\n\n\n- Historical data<\/strong>
<\/strong>The entire IP reputation history is taken into consideration when ISPs calculate the IP risk score.<\/li>\n\n\n\n- Shared vs Dedicated IPs<\/strong>
<\/strong>Shared IPs are affected by other users\u2019 behavior, whereas dedicated IPs reflect only your sending practices.<\/li>\n<\/ul>\n\n\n\nWhat is Domain reputation?<\/strong><\/h2>\n\n\n\nDomain reputation affects deliverability more than IP reputation. It is \u201cportable\u201d and follows you even when you change email service providers or IP addresses.<\/p>\n\n\n\n
Domain reputation is based on how recipients engage with your email domain. It feeds into the model alongside content heuristics and historical interaction signals.<\/p>\n\n\n\n
\n- Positive signals:<\/strong> Recipients respond, mark emails as important, and rarely mark them as spam.<\/li>\n\n\n\n
- Negative signals:<\/strong> Emails are ignored, rarely opened, or often marked as spam.<\/li>\n<\/ul>\n\n\n\n
Domain reputation is influenced by factors similar to IP reputation, but with a stronger emphasis on overall sender practices and recipient engagement<\/strong>.
Key factors include:<\/p>\n\n\n\n\n- Subscriber engagement,<\/li>\n\n\n\n
- Spam complaint rates, <\/li>\n\n\n\n
- Domain spoofing,<\/li>\n\n\n\n
- Proper configuration of email authentication protocols: SPF, DKIM and DMARC,<\/li>\n\n\n\n
- Domain age and warmup patterns also play a role. New domains or domains that begin sending large volumes without gradual warmup are viewed as higher-risk. Consistent, steady sending helps a domain build trust faster, especially during the early reputation-building period.<\/li>\n\n\n\n
- Blocklist appearances also have different effects: IP blocklisting can temporarily degrade delivery, while domain blocklisting is far more impactful and harder to recover from because it follows you across all sending systems.<\/li>\n<\/ul>\n\n\n\n
DKIM Selector Reputation<\/strong><\/h2>\n\n\n\n
Mailbox providers build reputation not only on the domain itself, but also per DKIM key\/selector. A DKIM selector is treated like its own \u201csending identity\u201d that collects reputation over time.
The combined layers are:
1. Domain reputation<\/strong> (d=domain.com)
This is the most influential layer as it is based on all traffic from DKIM selectors, SPF sending hosts, DMARC alignment results, historical good\/bad events, and overall brand trust.<\/p>\n\n\n\n2. Selector reputation<\/strong> (s=marketing, s=default)
Every selector has an impact on the overall domain. This is because mailbox providers view selectors and domains as interconnected identities. As a result, any negative reputation associated with a selector can adversely affect the domain’s reputation (d=).<\/p>\n\n\n\nAuthentication alignment at both the domain and selector levels can influence overall reputation, which naturally leads into understanding how alignment failures affect trust.
<\/p>\n\n\n\n
Authentication Alignment & Domain Trust<\/strong><\/h2>\n\n\n\nAuthentication alignment (how the visible From:<\/strong> domain lines up with the SPF MAIL FROM and DKIM d= domain) is a domain-level signal. When SPF or DKIM authenticate a message but the authenticated identifier does not<\/strong> align with the header From: domain, mailbox providers treat that as evidence the domain itself<\/em> is not in control of the message. That looks exactly like spoofing behavior \u2014 and spoofing is a domain-level threat.<\/p>\n\n\n\nReputation inheritance across subdomains <\/strong><\/h3>\n\n\n\nNow let\u2019s understand how subdomains are affected by the domain reputation. When we talk of email sending, a domain name usually refers to the primary web address of domain.com<\/em> which can have its extension such as mail.domain.com<\/em> as its subdomain. There also is an understanding of FQDN (Fully qualified domain name), which is the complete, specific address of a resource on the internet. For example:
In the address www.shop.example.com<\/strong> the \u201c.com<\/strong>\u201d is the top-level domain, \u201cexample<\/strong>\u201d is the second-level domain name, \u201cshop<\/strong>\u201d is the subdomain, and the \u201cwww<\/strong>\u201d is the hostname.<\/p>\n\n\n\nFor email, FQDN is the MAIL FROM domain which is used for bounce processing. Mailbox providers primarily evaluate this domain for reputation when processing inbound email.
There is a concept of reputation flowing up and down from the domain hierarchy. A very poor reputation on a subdomain can somehow negatively impact the parent domain and conversely, a strong main domain reputation can give a subdomain a boost.
One of the primary reasons for using subdomains is reputation segmentation. You can differentiate between marketing and transactional emails by setting individual subdomains for each and with the appropriate email volume and consistency a subdomain can develop its distinct reputation. This way you can isolate the reputation risk: if a marketing emails domain gets spam complaints, the transactional emails on a different subdomain are less likely to be affected.<\/p>\n\n\n\n
Why do modern MailBox Providers prioritize domain reputation over IP?<\/strong><\/h2>\n\n\n\n
<\/li>\n<\/ul>\n\n\n\n
How is your IP reputation score calculated?<\/strong><\/h2>\n\n\n\nMultiple factors can impact your IP reputation score. Key factors include:<\/p>\n\n\n\n
\n- Spam Complaints<\/strong>
Recipients flag an email as spam; high complaint rates significantly impact IP reputation.<\/li>\n\n\n\n- Bounce Rates<\/strong>
<\/strong>High percentages of hard or soft bounces indicate list issues. Soft bounces occur if inboxes are temporarily full; hard bounces occur for invalid or non-existent addresses.<\/li>\n\n\n\n- Blacklist listings<\/strong>
<\/strong>Inclusion in spam or threat databases (e.g Spamhaus) severely damages the IP reputation.<\/li>\n\n\n\n- Historical data<\/strong>
<\/strong>The entire IP reputation history is taken into consideration when ISPs calculate the IP risk score.<\/li>\n\n\n\n- Shared vs Dedicated IPs<\/strong>
<\/strong>Shared IPs are affected by other users\u2019 behavior, whereas dedicated IPs reflect only your sending practices.<\/li>\n<\/ul>\n\n\n\nWhat is Domain reputation?<\/strong><\/h2>\n\n\n\nDomain reputation affects deliverability more than IP reputation. It is \u201cportable\u201d and follows you even when you change email service providers or IP addresses.<\/p>\n\n\n\n
Domain reputation is based on how recipients engage with your email domain. It feeds into the model alongside content heuristics and historical interaction signals.<\/p>\n\n\n\n
\n- Positive signals:<\/strong> Recipients respond, mark emails as important, and rarely mark them as spam.<\/li>\n\n\n\n
- Negative signals:<\/strong> Emails are ignored, rarely opened, or often marked as spam.<\/li>\n<\/ul>\n\n\n\n
Domain reputation is influenced by factors similar to IP reputation, but with a stronger emphasis on overall sender practices and recipient engagement<\/strong>.
Key factors include:<\/p>\n\n\n\n\n- Subscriber engagement,<\/li>\n\n\n\n
- Spam complaint rates, <\/li>\n\n\n\n
- Domain spoofing,<\/li>\n\n\n\n
- Proper configuration of email authentication protocols: SPF, DKIM and DMARC,<\/li>\n\n\n\n
- Domain age and warmup patterns also play a role. New domains or domains that begin sending large volumes without gradual warmup are viewed as higher-risk. Consistent, steady sending helps a domain build trust faster, especially during the early reputation-building period.<\/li>\n\n\n\n
- Blocklist appearances also have different effects: IP blocklisting can temporarily degrade delivery, while domain blocklisting is far more impactful and harder to recover from because it follows you across all sending systems.<\/li>\n<\/ul>\n\n\n\n
DKIM Selector Reputation<\/strong><\/h2>\n\n\n\n
Mailbox providers build reputation not only on the domain itself, but also per DKIM key\/selector. A DKIM selector is treated like its own \u201csending identity\u201d that collects reputation over time.
The combined layers are:
1. Domain reputation<\/strong> (d=domain.com)
This is the most influential layer as it is based on all traffic from DKIM selectors, SPF sending hosts, DMARC alignment results, historical good\/bad events, and overall brand trust.<\/p>\n\n\n\n2. Selector reputation<\/strong> (s=marketing, s=default)
Every selector has an impact on the overall domain. This is because mailbox providers view selectors and domains as interconnected identities. As a result, any negative reputation associated with a selector can adversely affect the domain’s reputation (d=).<\/p>\n\n\n\nAuthentication alignment at both the domain and selector levels can influence overall reputation, which naturally leads into understanding how alignment failures affect trust.
<\/p>\n\n\n\n
Authentication Alignment & Domain Trust<\/strong><\/h2>\n\n\n\nAuthentication alignment (how the visible From:<\/strong> domain lines up with the SPF MAIL FROM and DKIM d= domain) is a domain-level signal. When SPF or DKIM authenticate a message but the authenticated identifier does not<\/strong> align with the header From: domain, mailbox providers treat that as evidence the domain itself<\/em> is not in control of the message. That looks exactly like spoofing behavior \u2014 and spoofing is a domain-level threat.<\/p>\n\n\n\nReputation inheritance across subdomains <\/strong><\/h3>\n\n\n\nNow let\u2019s understand how subdomains are affected by the domain reputation. When we talk of email sending, a domain name usually refers to the primary web address of domain.com<\/em> which can have its extension such as mail.domain.com<\/em> as its subdomain. There also is an understanding of FQDN (Fully qualified domain name), which is the complete, specific address of a resource on the internet. For example:
In the address www.shop.example.com<\/strong> the \u201c.com<\/strong>\u201d is the top-level domain, \u201cexample<\/strong>\u201d is the second-level domain name, \u201cshop<\/strong>\u201d is the subdomain, and the \u201cwww<\/strong>\u201d is the hostname.<\/p>\n\n\n\nFor email, FQDN is the MAIL FROM domain which is used for bounce processing. Mailbox providers primarily evaluate this domain for reputation when processing inbound email.
There is a concept of reputation flowing up and down from the domain hierarchy. A very poor reputation on a subdomain can somehow negatively impact the parent domain and conversely, a strong main domain reputation can give a subdomain a boost.
One of the primary reasons for using subdomains is reputation segmentation. You can differentiate between marketing and transactional emails by setting individual subdomains for each and with the appropriate email volume and consistency a subdomain can develop its distinct reputation. This way you can isolate the reputation risk: if a marketing emails domain gets spam complaints, the transactional emails on a different subdomain are less likely to be affected.<\/p>\n\n\n\n
Why do modern MailBox Providers prioritize domain reputation over IP?<\/strong><\/h2>\n\n\n\n
Recipients flag an email as spam; high complaint rates significantly impact IP reputation.<\/li>\n\n\n\n
<\/strong>High percentages of hard or soft bounces indicate list issues. Soft bounces occur if inboxes are temporarily full; hard bounces occur for invalid or non-existent addresses.<\/li>\n\n\n\n
<\/strong>Inclusion in spam or threat databases (e.g Spamhaus) severely damages the IP reputation.<\/li>\n\n\n\n
<\/strong>The entire IP reputation history is taken into consideration when ISPs calculate the IP risk score.<\/li>\n\n\n\n
<\/strong>Shared IPs are affected by other users\u2019 behavior, whereas dedicated IPs reflect only your sending practices.<\/li>\n<\/ul>\n\n\n\n
What is Domain reputation?<\/strong><\/h2>\n\n\n\nDomain reputation affects deliverability more than IP reputation. It is \u201cportable\u201d and follows you even when you change email service providers or IP addresses.<\/p>\n\n\n\n
Domain reputation is based on how recipients engage with your email domain. It feeds into the model alongside content heuristics and historical interaction signals.<\/p>\n\n\n\n
\n- Positive signals:<\/strong> Recipients respond, mark emails as important, and rarely mark them as spam.<\/li>\n\n\n\n
- Negative signals:<\/strong> Emails are ignored, rarely opened, or often marked as spam.<\/li>\n<\/ul>\n\n\n\n
Domain reputation is influenced by factors similar to IP reputation, but with a stronger emphasis on overall sender practices and recipient engagement<\/strong>.
Key factors include:<\/p>\n\n\n\n\n- Subscriber engagement,<\/li>\n\n\n\n
- Spam complaint rates, <\/li>\n\n\n\n
- Domain spoofing,<\/li>\n\n\n\n
- Proper configuration of email authentication protocols: SPF, DKIM and DMARC,<\/li>\n\n\n\n
- Domain age and warmup patterns also play a role. New domains or domains that begin sending large volumes without gradual warmup are viewed as higher-risk. Consistent, steady sending helps a domain build trust faster, especially during the early reputation-building period.<\/li>\n\n\n\n
- Blocklist appearances also have different effects: IP blocklisting can temporarily degrade delivery, while domain blocklisting is far more impactful and harder to recover from because it follows you across all sending systems.<\/li>\n<\/ul>\n\n\n\n
DKIM Selector Reputation<\/strong><\/h2>\n\n\n\n
Mailbox providers build reputation not only on the domain itself, but also per DKIM key\/selector. A DKIM selector is treated like its own \u201csending identity\u201d that collects reputation over time.
The combined layers are:
1. Domain reputation<\/strong> (d=domain.com)
This is the most influential layer as it is based on all traffic from DKIM selectors, SPF sending hosts, DMARC alignment results, historical good\/bad events, and overall brand trust.<\/p>\n\n\n\n2. Selector reputation<\/strong> (s=marketing, s=default)
Every selector has an impact on the overall domain. This is because mailbox providers view selectors and domains as interconnected identities. As a result, any negative reputation associated with a selector can adversely affect the domain’s reputation (d=).<\/p>\n\n\n\nAuthentication alignment at both the domain and selector levels can influence overall reputation, which naturally leads into understanding how alignment failures affect trust.
<\/p>\n\n\n\n
Authentication Alignment & Domain Trust<\/strong><\/h2>\n\n\n\nAuthentication alignment (how the visible From:<\/strong> domain lines up with the SPF MAIL FROM and DKIM d= domain) is a domain-level signal. When SPF or DKIM authenticate a message but the authenticated identifier does not<\/strong> align with the header From: domain, mailbox providers treat that as evidence the domain itself<\/em> is not in control of the message. That looks exactly like spoofing behavior \u2014 and spoofing is a domain-level threat.<\/p>\n\n\n\nReputation inheritance across subdomains <\/strong><\/h3>\n\n\n\nNow let\u2019s understand how subdomains are affected by the domain reputation. When we talk of email sending, a domain name usually refers to the primary web address of domain.com<\/em> which can have its extension such as mail.domain.com<\/em> as its subdomain. There also is an understanding of FQDN (Fully qualified domain name), which is the complete, specific address of a resource on the internet. For example:
In the address www.shop.example.com<\/strong> the \u201c.com<\/strong>\u201d is the top-level domain, \u201cexample<\/strong>\u201d is the second-level domain name, \u201cshop<\/strong>\u201d is the subdomain, and the \u201cwww<\/strong>\u201d is the hostname.<\/p>\n\n\n\nFor email, FQDN is the MAIL FROM domain which is used for bounce processing. Mailbox providers primarily evaluate this domain for reputation when processing inbound email.
There is a concept of reputation flowing up and down from the domain hierarchy. A very poor reputation on a subdomain can somehow negatively impact the parent domain and conversely, a strong main domain reputation can give a subdomain a boost.
One of the primary reasons for using subdomains is reputation segmentation. You can differentiate between marketing and transactional emails by setting individual subdomains for each and with the appropriate email volume and consistency a subdomain can develop its distinct reputation. This way you can isolate the reputation risk: if a marketing emails domain gets spam complaints, the transactional emails on a different subdomain are less likely to be affected.<\/p>\n\n\n\n
Why do modern MailBox Providers prioritize domain reputation over IP?<\/strong><\/h2>\n\n\n\n
Domain reputation is influenced by factors similar to IP reputation, but with a stronger emphasis on overall sender practices and recipient engagement<\/strong>. 2. Selector reputation<\/strong> (s=marketing, s=default) Authentication alignment at both the domain and selector levels can influence overall reputation, which naturally leads into understanding how alignment failures affect trust. Authentication alignment (how the visible From:<\/strong> domain lines up with the SPF MAIL FROM and DKIM d= domain) is a domain-level signal. When SPF or DKIM authenticate a message but the authenticated identifier does not<\/strong> align with the header From: domain, mailbox providers treat that as evidence the domain itself<\/em> is not in control of the message. That looks exactly like spoofing behavior \u2014 and spoofing is a domain-level threat.<\/p>\n\n\n\n Now let\u2019s understand how subdomains are affected by the domain reputation. When we talk of email sending, a domain name usually refers to the primary web address of domain.com<\/em> which can have its extension such as mail.domain.com<\/em> as its subdomain. There also is an understanding of FQDN (Fully qualified domain name), which is the complete, specific address of a resource on the internet. For example: For email, FQDN is the MAIL FROM domain which is used for bounce processing. Mailbox providers primarily evaluate this domain for reputation when processing inbound email.
Key factors include:<\/p>\n\n\n\n\n
DKIM Selector Reputation<\/strong><\/h2>\n\n\n\n
Mailbox providers build reputation not only on the domain itself, but also per DKIM key\/selector. A DKIM selector is treated like its own \u201csending identity\u201d that collects reputation over time.
The combined layers are:
1. Domain reputation<\/strong> (d=domain.com)
This is the most influential layer as it is based on all traffic from DKIM selectors, SPF sending hosts, DMARC alignment results, historical good\/bad events, and overall brand trust.<\/p>\n\n\n\n
Every selector has an impact on the overall domain. This is because mailbox providers view selectors and domains as interconnected identities. As a result, any negative reputation associated with a selector can adversely affect the domain’s reputation (d=).<\/p>\n\n\n\n
<\/p>\n\n\n\nAuthentication Alignment & Domain Trust<\/strong><\/h2>\n\n\n\n
Reputation inheritance across subdomains <\/strong><\/h3>\n\n\n\n
In the address www.shop.example.com<\/strong> the \u201c.com<\/strong>\u201d is the top-level domain, \u201cexample<\/strong>\u201d is the second-level domain name, \u201cshop<\/strong>\u201d is the subdomain, and the \u201cwww<\/strong>\u201d is the hostname.<\/p>\n\n\n\n
There is a concept of reputation flowing up and down from the domain hierarchy. A very poor reputation on a subdomain can somehow negatively impact the parent domain and conversely, a strong main domain reputation can give a subdomain a boost.
One of the primary reasons for using subdomains is reputation segmentation. You can differentiate between marketing and transactional emails by setting individual subdomains for each and with the appropriate email volume and consistency a subdomain can develop its distinct reputation. This way you can isolate the reputation risk: if a marketing emails domain gets spam complaints, the transactional emails on a different subdomain are less likely to be affected.<\/p>\n\n\n\nWhy do modern MailBox Providers prioritize domain reputation over IP?<\/strong><\/h2>\n\n\n\n
![\"\"](\"https:\/\/mail-tester.am\/blog\/wp-content\/uploads\/2026\/03\/1-1024x425.png\")
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