Domain

Runtime verified Test scripts included

Syntax

Domain(emailAddress)  →  string

1 argument — exactly

Parameters

Name	Type	Required	Description
`emailAddress`	string	Yes	Email address; the text after the first at sign is returned verbatim

Example

%%[ VAR @d SET @d = Domain("tomas.q@example.com") ]%%
%%=v(@d)=%%

Renders example.com.

Routing on the domain means folding the case first, because the result keeps whatever casing the address had:

%%[
  VAR @d
  SET @d = Lowercase(Domain(emailaddr))
]%%
%%=IIf(@d == "example.com", "internal recipient", "external recipient")=%%

Return value

string — the text following the first at sign.

There is no closed set of sentinel values to test for. An input with no at sign, an empty string, a bare at sign, an at sign with nothing after it and a number all render nothing at all; the docs describe those cases as a null return, and on a page that is an empty value. Use Empty to detect it rather than comparing against a literal.

Behaviour

The split is on the first at sign, and the rest is returned verbatim. Domain("a@b@example.com") gives b@example.com — the second at sign is part of the result, not a reason to fail.

A multi-level domain comes back whole. Domain("tomas.q@a.b.example.co.uk") gives a.b.example.co.uk, and a five-label domain returns all five labels. Nothing is reduced to a registrable domain.

The original casing is preserved. Domain("Tomas.Q@Example.COM") gives Example.COM, so a comparison against a lowercase allow-list needs Lowercase around it.

No validation happens. Values that IsEmailAddress rejects still produce a domain: Domain("tomas q@example.com") gives example.com and Domain("hello@world") gives world. Validate first if that matters.

A plus tag in the local part changes nothing. Domain("tomas.q+news@example.com") gives example.com.

What comes back for each shape

Call	Renders
`Domain("tomas.q@example.com")`	`example.com`
`Domain("tomas.q+news@example.com")`	`example.com`
`Domain("tomas.q@a.b.example.co.uk")`	`a.b.example.co.uk`
`Domain("a@b@example.com")`	`b@example.com`
`Domain("Tomas.Q@Example.COM")`	`Example.COM`
`Domain("hello@world")`	`world`
`Domain("example.com")`	(empty)
`Domain("tomas.q@")`	(empty)
`Domain("@")`	(empty)
`Domain("")`	(empty)
`Domain(123)`	(empty)

Show test script

%%[
  VAR @b
  SET @b = RequestParameter("b")

  /* known-good control: renders on every request, so a run of HTTP 422s
     can be told apart from a broken deploy */
  OutputLine(Concat("CTRL=[", Uppercase("ok"), "]"))

  /* what is extracted, for the shapes a caller actually meets */
  OutputLine(Concat("--- D start ---"))
  OutputLine(Concat("D1_plain=[", Domain("tomas.q@example.com"), "]"))
  OutputLine(Concat("D2_no_at=[", Domain("example.com"), "]"))
  OutputLine(Concat("D3_multilevel=[", Domain("tomas.q@a.b.example.co.uk"), "]"))
  OutputLine(Concat("D4_double_at=[", Domain("a@b@example.com"), "]"))
  OutputLine(Concat("D5_plustag=[", Domain("tomas.q+news@example.com"), "]"))
  OutputLine(Concat("D6_upper=[", Domain("Tomas.Q@Example.COM"), "]"))
  OutputLine(Concat("--- D done ---"))

  /* the empty string, in its own branch: the sibling IsCHTMLBrowser aborts
     on it, so the four functions must not share one empty-string branch */
  IF @b == "d_empty" THEN
    OutputLine(Concat("--- d_empty start ---"))
    OutputLine(Concat("D_EMPTY=[", Domain(""), "]"))
    OutputLine(Concat("--- d_empty done ---"))
  ENDIF

  /* degenerate at-sign placements and a value no validator would accept */
  IF @b == "d_edge" THEN
    OutputLine(Concat("--- d_edge start ---"))
    OutputLine(Concat("D_AT_ONLY=[", Domain("@"), "]"))
    OutputLine(Concat("D_TRAIL_AT=[", Domain("tomas.q@"), "]"))
    OutputLine(Concat("D_SPACE=[", Domain("tomas q@example.com"), "]"))
    OutputLine(Concat("D_NOT_EMAIL=[", Domain("hello@world"), "]"))
    OutputLine(Concat("D_MULTI2=[", Domain("x@sub.a.b.example.co.uk"), "]"))
    OutputLine(Concat("--- d_edge done ---"))
  ENDIF

  /* a non-string argument */
  IF @b == "g_num" THEN
    OutputLine(Concat("--- g_num start ---"))
    OutputLine(Concat("D_NUM=[", Domain(123), "]"))
    OutputLine(Concat("--- g_num done ---"))
  ENDIF

  /* the empty result confirmed with a second function rather than read off
     a blank pair of brackets */
  IF @b == "g_tok" THEN
    OutputLine(Concat("--- g_tok start ---"))
    OutputLine(Concat("D_NULLCHK=[", IIf(Empty(Domain("example.com")), "domain-empty", "domain-not-empty"), "]"))
    OutputLine(Concat("--- g_tok done ---"))
  ENDIF
]%%

OutputLine needs Concat

Every marker and label in the test script goes through Concat(...), including single-argument ones. A bare string literal passed to OutputLine renders an empty line while the page still returns HTTP 200, so the marker silently vanishes.

Availability

Platform	Available
Marketing Cloud Engagement	Yes
Marketing Cloud Next	No