SMTBot

seo SMTBot

SimilarTech web crawler for technology detection

About this crawler

SMTBot is a web crawler identified by the regular-expression pattern SMTBot in the User-Agent request header. It is categorised as seo. Use the regex above to detect, log, allow, or block SMTBot traffic in your web server, CDN edge rules, or robots.txt.

Block-rate · top 25k sites

0.39%
latest snapshot
2026-06-04
matched key: SMTBot
2026-05-012026-06-040.62%

Technical details

Name
SMTBot
Pattern
SMTBot
Tags
seo
Reference
http://www.similartech.com/smtbot
Added
2014/10/04
rDNS suffixes
.smtbot.com
Instances
5 known sample(s)

rDNS verification (FCrDNS)

Verify a request is genuinely SMTBot with forward-confirmed reverse DNS: the client IP's PTR record must end in one of the suffixes below and a forward A/AAAA lookup of that hostname must return the same IP. UA strings alone are spoofable; FCrDNS is not.

Sample User-Agent strings

Mozilla/5.0 (compatible; SMTBot/1.0; +http://www.similartech.com/smtbot)
SMTBot (similartech.com/smtbot)
Mozilla/5.0 (iPhone; CPU iPhone OS 6_0 like Mac OS X) AppleWebKit/536.26 (KHTML, like Gecko) Version/6.0 Mobile/10A5376e Safari/8536.25 (compatible; SMTBot/1.0; +http://www.similartech.com/smtbot)
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.75 Safari/537.36 (compatible; SMTBot/1.0; +http://www.similartech.com/smtbot)
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/68.0.3440.75 Safari/537.36 (compatible; SMTBot/1.0; http://www.similartech.com/smtbot)

Block this crawler

robots.txt — disallow SMTBot:

User-agent: SMTBot Disallow: /

Apache .htaccess — return 403:

RewriteEngine On RewriteCond %{HTTP_USER_AGENT} SMTBot [NC] RewriteRule .* - [F,L]

Nginx — return 403 inside a server block:

if ($http_user_agent ~* "SMTBot") { return 403; }
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