Summary
Identifying the SMTP provider from an MX record is achieved by querying the domain's DNS records to find its MX records. These records specify the mail servers responsible for handling email delivery. Experts and marketers suggest various methods, including using DNS lookup tools (like `nslookup`, `dig`, MXToolbox, and DNSWatch), analyzing the hostnames in the MX records (often revealing the provider's name), and using search engines for context. The MX record contains priority and hostname information, where the hostname indicates the inbound mail server. Analyzing passive DNS data and understanding domain wildcarding can offer further insights. While a direct mechanical determination is not always possible, combining these techniques significantly aids in identifying the SMTP provider.
Key findings
- MX Records: Key Information Source: MX records directly point to the mail servers responsible for handling email for a domain, providing a primary source of information.
- Hostname Analysis: Direct Identification: Analyzing the hostname within the MX record can directly reveal the SMTP provider, particularly if the provider's name is included (e.g., smtp.google.com).
- DNS Lookup Tools: Essential for Querying: DNS lookup tools like `nslookup`, `dig`, MXToolbox, and DNSWatch are essential for querying and retrieving MX record information.
- Search Engines and Context: Supplemental Research: Using search engines and analyzing context can supplement direct lookup methods, especially when mechanical determination is not straightforward.
Key considerations
- No Guaranteed Mechanical Method: There is no guarantee of directly and mechanically determining the provider solely from the hostname; research and context might be required.
- Understanding Domain Wildcarding: Understanding how domains are wildcarded and which servers handle primary vs. secondary MX can influence accurate identification.
- Analyzing passive DNS Data: Analyzing passive DNS can reveal relationships, such as multiple entities pointing to the same MX, which can hint to provider relationships.
What email marketers say
8 marketer opinions
Identifying the SMTP provider from an MX record involves examining the MX records associated with a domain. These records, which specify the mail servers responsible for accepting email, can be queried using tools like `nslookup`, `dig`, or online MX lookup services. Analyzing the hostnames listed in the MX records often reveals the email provider, particularly if the hostname contains the provider's name. The MX record contains a priority and a hostname, where the hostname is the server accepting inbound mail, making it possible to identify the ESP being used.
Key opinions
- MX Records Indicate Mail Servers: MX records specify the mail servers configured to receive email on behalf of a domain.
- Hostname Reveals Provider: Analyzing hostnames in MX records can reveal the email provider, especially if the provider's name is included (e.g., smtp.google.com).
- Tools Aid Identification: Tools like `nslookup`, `dig`, MXToolbox, and DNSWatch can be used to query and examine MX records.
- Hostname and Priority: Each MX record contains a hostname and a priority. The hostname is the mail server, and reading it provides a direct method of identifying which ESP is being used.
Key considerations
- Log Analysis for Brands: Log analysis may sometimes be necessary to identify the specific brand associated with the email provider (e.g., brand.safesysmail.com).
- Relying on Hostname Conventions: Identification relies on the hostname following recognizable naming conventions (e.g., including the provider's name).
Marketer view
Email marketer from Neil Patel's Blog shares that MX records indicate which servers are configured to receive email on behalf of a domain. By examining the MX records, you can often identify the email service provider responsible for handling email for that domain.
29 Oct 2021 - Neil Patel's Blog
Marketer view
Email marketer from Reddit shares that analyzing the hostnames listed in the MX records can often reveal the email provider, especially if the hostnames contain the provider's name (e.g., smtp.google.com, mx.zoho.com).
1 Jan 2023 - Reddit
What the experts say
7 expert opinions
Identifying an SMTP provider from an MX record involves a combination of techniques. Initial methods include using search engines like Google to research the MX name and identify potential matches. While there isn't always a direct mechanical method, context and passive DNS analysis can help deduce the provider. Examining how domains are wildcarded and where they point (primary vs. secondary MX) gives additional clues. MX records fundamentally show where to send email, which directly leads to the responsible mail server and often reveals the ESP.
Key opinions
- Google and Context are Helpful: Using Google and reading the context surrounding the MX record can help identify the SMTP provider, especially when a direct lookup isn't possible.
- Passive DNS Analysis: Passive DNS analysis, such as through Domaintools, can reveal patterns and connections, like multiple banks pointing to the same MX record.
- Wildcard Domains: Understanding how domains are wildcarded and where they point (primary vs. secondary MX) gives additional clues about the ESP's infrastructure.
- MX Records Reveal Destination: MX records inherently show where the internet sends email for a domain, directly revealing the responsible mail server and often the ESP.
Key considerations
- No Mechanical Guarantee: There is no guaranteed mechanical way to determine the company name from a hostname; context and research are often necessary.
- Redundancy: SMTP inherently has redundancy which is worth considering.
Expert view
Expert from Email Geeks responds to a question about single point of failure, shares that SMTP has its own redundancy, so it is not a single point of failure.
16 Feb 2023 - Email Geeks
Expert view
Expert from Email Geeks explains that *.safesysmail.com is wildcarded to a single IP that accepts inbound mail on port 25. Brands are set up to MX to the whitelabel wildcard domain as primary, and smtp.safesysmail.com as secondary.
25 Dec 2024 - Email Geeks
What the documentation says
4 technical articles
Identifying the SMTP provider from an MX record involves using DNS lookup tools to query the MX record of a domain. The MX record specifies the mail servers responsible for accepting email messages on behalf of that domain, which helps identify the email provider. The hostname with the lowest preference number typically indicates the primary SMTP server. Tools like MXToolbox streamline this process by querying DNS records for mail servers and their priority.
Key findings
- MX Records Key for Routing: MX records are essential for email routing, as specified in RFC 5321.
- Lowest Preference is Primary: The hostname with the lowest preference number in the MX record is typically the primary SMTP server.
- DNS Lookup Tools Essential: DNS lookup tools are necessary to query MX records and identify mail servers and their priorities.
- MXToolbox Streamlines Process: Tools like MXToolbox query DNS records for mail servers and their priority to point indirectly to the email provider.
Key considerations
- Reliance on Accurate DNS Records: Identification accuracy relies on accurate and up-to-date DNS records.
- Preference Numbers: The MX record with the lowest preference number, while typically the primary, may not always directly correspond to the intended provider.
Technical article
Documentation from Cloudflare shares that MX records are essential for email routing and specify the mail servers responsible for accepting email messages on behalf of a domain. Examining these records allows you to determine which provider handles email services.
17 Oct 2021 - Cloudflare
Technical article
Documentation from Google Workspace Admin Help explains that you can find the SMTP server hostname in the MX record. Use a DNS lookup tool and query for the MX record of the domain. The hostname with the lowest preference number is typically the primary SMTP server.
24 Dec 2024 - Google Workspace Admin Help
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