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Skip the IDNA round trip for domains without Punycode labels #182

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Merged
JoshData merged 2 commits into from
Nov 8, 2026
Merged

Skip the IDNA round trip for domains without Punycode labels #182

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b9b3fdd
Skip the IDNA round trip for domains without Punycode labels
John-Cusack Oct 29, 2026
241dc9e
Merge branch 'main' into tier1-pure-python-speedup
JoshData Nov 8, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ In Development
* add support python3.15
* The IPv6 tag of a domain literal is now case-insensitive, as in the RFCs, so `me@[ipv6:::1]` is accepted (and normalized to `me@[IPv6:::1]`) when `allow_domain_literal=True`.
* Internationalized domains with a right-to-left label are now rejected if any other label breaks the IDNA Bidi Rule (RFC 5893), such as a label starting with a digit. Such domains, like `1.xn--4dbc.com` and `xn--4dbc.1.com` (`1.אב.com` and `אב.1.com` in Unicode), could be displayed identically.
* Faster validation of domains without Punycode (xn--) labels.

2.3.0 (August 26, 2025)
-----------------------
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7 changes: 7 additions & 0 deletions email_validator/syntax.py
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Expand Up @@ -651,6 +651,13 @@ def validate_email_domain_name(domain: str, test_environment: bool = False, glob
if ascii_domain == d or ascii_domain.endswith("." + d):
raise EmailSyntaxError("The part after the @-sign is a special-use or reserved name that cannot be used with email.")

# Domains without Punycode labels come back unchanged from the IDNA round trip below.
if "xn--" not in ascii_domain:
return {
"ascii_domain": ascii_domain,
"domain": ascii_domain,
}

# We may have been given an IDNA ASCII domain to begin with. Check
# that the domain actually conforms to IDNA. It could look like IDNA
# but not be actual IDNA. For ASCII-only domains, the conversion out
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