---
title: "Pros and cons of using wildcarding in SPF | AutoSPF"
description: "SPF is the email authentication protocol that allows domain owners to specify which mail servers they officially allow to be used to send emails on behalf of a."
image: "https://autospf.com/og/blog/pros-and-cons-of-using-wildcarding-in-spf.png"
canonical: "https://autospf.com/blog/pros-and-cons-of-using-wildcarding-in-spf/"
---

Quick Answer

SPF is the email authentication protocol that allows domain owners to specify which mail servers they officially allow to send emails on behalf of a domain. Wildcarding in SPF uses the \* mechanism, matching any domain or IP that does not explicitly match other mechanisms in the record. Wildcarding usually simplifies SPF records.

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![Pros and cons of using wildcarding](https://media.mailhop.org/autospf/images/2025/01/spf-flattening-8713.jpg) 

SPF is the email authentication protocol that allows domain owners to specify which [mail servers](https://www.cloudflare.com/learning/email-security/what-is-a-mail-server/) they officially allow to be used to send emails on behalf of a domain. Wildcarding in SPF is done using the ‘\*’ mechanism. It matches any domain or IP that doesn’t explicitly match other mechanisms in the record. Wildcarding usually simplifies [SPF records](/spf-record-checker/create-spf-record/); however, at times, it introduces risks. 

Here is a list of the pros and cons of [wildcarding in SPF](/blog/pros-and-cons-of-using-wildcarding-in-spf/). It’s up to you to decide which one weighs more for your situation. You can accordingly decide whether to use or avoid wildcarding.

## Pros of using wildcarding in SPF

### 1\. Ease of configuration

_With wildcarding, it becomes a lot easier to configure SPF records with the correct set of mechanisms, modifiers, and qualifiers_. This is more useful for domains that have many subdomains linked to them or for companies that frequently add new subdomains. So, with wildcarding, you don’t have to explicitly list each subdomain or IP. In such scenarios, wildcarding behaves as a catch-all.

_For example, v=spf1 \* \~all allows all servers to send emails on behalf of a domain._

### 2\. Handles unforeseen subdomains

If a new subdomain is created, wildcarding ensures that emails from these subdomains will pass [SPF checks](/spf-record-checker/) without requiring updates to the SPF record.

### 3\. Minimizes maintenance overhead

If you run a company with multiple employees, you will know how difficult it is to deal with dynamic IPs or [third-party services](https://securityscorecard.com/blog/what-is-a-third-party-service-provider/). Maintaining a well-updated list of authorized senders becomes cumbersome. _However, by introducing wildcarding, you can reduce the need for constant updates_. 

![dynamic IPs](https://media.mailhop.org/autospf/images/2025/01/spf-lookup-3.jpg) 

### 4\. Compatibility with dynamic environments

Organizations using ephemeral IPs or frequently changing infrastructure (e.g., cloud services) benefit from wildcarding since it accommodates changes without requiring immediate SPF updates.

### 5\. Fallback mechanisms for legitimate but unexpected senders

If [legitimate emails](https://www.usatoday.com/story/tech/2021/08/23/gmail-spam-filter-email-inbox-google/8242847002/) are sent from an unlisted IP or subdomain, wildcarding prevents these emails from failing SPF checks, reducing the chances of email delivery issues.

## Cons of using wildcarding in SPF

### 1\. Increased security risks

Wildcarding allows any server to be used to send emails from your domain. [Threat actors](https://www.nbcnews.com/tech/security/us-treasury-says-computers-hacked-chinese-threat-actor-rcna185809) leverage this to send [phishing and spoofing emails](https://www.bleepingcomputer.com/news/google/google-now-blocks-spoofed-emails-for-better-phishing-protection/) in the name of your organization. This ultimately defies the purpose of implementing SPF in the first place.

Example Scenario:

If you use v=spf1 \* \~all, a [malicious actor](https://www.theguardian.com/technology/2024/mar/25/us-sanctions-chinese-hackers) can spoof your domain to send phishing emails, and those emails will pass SPF checks.

### 2\. Difficulty in tracing issues

It will get really difficult to trace the source of a malicious or [unauthorized email](https://news.trendmicro.com/2023/12/05/unauthorized-log-in-attempt-notification-email/) if you have used a wildcard in your SPF record. This happens because [SPF](/blog/what-is-spf-email-a-guide-to-sender-validation-technology/) is designed to compare the sending server’s IP address or domain against the mechanisms in the SPF record. However, the ‘\*’ mechanism matches any domain or [IP address](https://www.investopedia.com/terms/i/ip-address.asp) that doesn’t explicitly match another mechanism in the record.

### 3\. Degrades email authentication standards

_Wildcarding conflicts with best practices for email authentication, especially when used alongside DMARC_. It creates ambiguity, making [DMARC](/10-reasons-for-regular-spf-record-checks-in-cybersecurity/dmarc-record-check/) enforcement less effective.

![email security](https://media.mailhop.org/autospf/images/2025/01/spf-permerror-6713.jpg) 

Wildcarding can simplify SPF management, but it isn’t considered a best practice because of the significant risks associated with it. The convenience it offers comes at the cost of compromised [email security](/) and [domain reputation](https://www.activecampaign.com/blog/domain-reputation). To mitigate risks and enhance security, we suggest striving for precise SPF configurations and regularly auditing your [email authentication](/spf-too-many-dns-lookups/spf-lookup/) protocols.

## How DNS wildcards actually behave with SPF

**SPF does not support true DNS wildcards the way most people assume.** A wildcard TXT record like `*.example.com IN TXT "v=spf1 ..."` only matches subdomains that do NOT already have their own TXT records, and many DNS providers do not permit wildcard TXT records in the first place. [RFC 7208](https://datatracker.ietf.org/doc/html/rfc7208) defines SPF lookups on a per-domain basis: the receiving mail server queries the exact domain in the `MAIL FROM` envelope, and if no SPF record exists there it returns `none`, which is equivalent to no protection at all.

The practical consequence is that any subdomain without an explicit SPF record can be spoofed, even when the parent domain has a locked-down `-all` policy. Attackers routinely scan for unprotected subdomains (`mail.`, `smtp.`, `sales.`, `hr.`, stale DNS entries) and spoof messages from those instead of the well-protected apex.

If you do use wildcards, apply them only to domains that are never used for sending emails. For domains that do send email, targeted and selective SPF configurations offer much stronger defenses against [phishing and spoofing](https://thehackernews.com/2024/07/proofpoint-email-routing-flaw-exploited.html).

## Topics

[ DMARC ](/tags/dmarc/)[ email security ](/tags/email-security/)[ SPF ](/tags/spf/)[ SPF record ](/tags/spf-record/) 

![Brad Slavin](https://media.mailhop.org/autospf/images/authors/brad-slavin.jpg) 

[ Brad Slavin ](/authors/brad-slavin/) 

General Manager

Founder and General Manager of DuoCircle. Product strategy and commercial lead for AutoSPF's 2,000+ customer base.

[LinkedIn Profile →](https://www.linkedin.com/in/bradslavin) 

## Ready to get started?

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[ Book a Demo ](/book-a-demo/) 

## Related Articles

[  Advanced 10m  AutoSPF’s Guide to Configuring SPF & DKIM for Avanan: A Detailed Walk-through  Nov 26, 2025 ](/blog/autospf-guide-configuring-spf-dkim-for-avanan-detailed-setup-walkthrough/)[  Advanced 24m  Best DNS Security Tools for Email in 2026 SPF, DKIM & DMARC Management Compared  Apr 28, 2026 ](/blog/best-dns-security-tools-email-2026-spf-dkim-dmarc-compared/)[  Advanced 23m  Best Email Authentication Tools For Enterprise in 2026 The Complete Guide  Apr 30, 2026 ](/blog/best-email-authentication-tools-enterprise-2026-complete-guide-solutions/)[  Advanced 30m  Best SPF Management Tools for MSPs in 2026 A Buyer’s Guide  Apr 27, 2026 ](/blog/best-spf-management-tools-for-msps-in-2026-buyers-guide/)

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