B4X

Extract Linked Domains from an HTML Email

Demonstrates the Chilkat Email.LinkedDomains method, which extracts the domain names from the hyperlinks in an HTML email. Lowercase domains are appended to a StringTable without creating duplicates. This example sets an HTML body with several links and lists the distinct domains.

Background: The set of domains a message links to is a strong signal for spam and phishing analysis — legitimate mail usually points at a few expected domains, while abusive mail often hides links to many unrelated or look-alike hosts. LinkedDomains gives you that de-duplicated list directly. Note it only parses the links; it does not fetch them, so no network request is made.

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Dim success As Boolean = False

'  Demonstrates the LinkedDomains method, which extracts the domain names from the
'  hyperlinks in an HTML email.  Lowercase domains are appended to a StringTable without
'  creating duplicates.

Dim email As ChilkatEmail
email.Initialize
email.Subject = "LinkedDomains example"

'  An HTML body containing several hyperlinks.
email.SetHtmlBody("<html><body>Visit <a href=" & Chr(34) & "https://www.example.com/page" & Chr(34) & ">Example</a>, <a href=" & Chr(34) & "http://sales.contoso.com" & Chr(34) & ">Contoso</a>, and <a href=" & Chr(34) & "https://www.example.com/other" & Chr(34) & ">Example again</a>.</body></html>")

'  Extract the linked domains into a StringTable.
Dim domains As ChilkatStringTable
domains.Initialize

success = email.LinkedDomains(domains)
If success = False Then
    Log(email.LastErrorText)
    Return
End If


Dim n As Int = domains.Count
Dim i As Int
For i = 0 To n - 1
    Log(domains.StringAt(i))
Next