Regexes in Aliases

What Are Regex Aliases?

Use regular expressions to match patterns in email aliases and forward them dynamically. This lets you handle multiple similar addresses with a single rule.

A common pattern that you can set up easily:

Using substitutions

You can use $1, $2, etc. to insert values matched by regex groups (parentheses) into the destination email address.

• $1 = first matched group, $2 = second group, and so on.
• This allows you to dynamically forward emails based on parts of the alias.

Example:

Let's say you have an alias defined as:

If someone sends an email to: john.doe@yourdomain.com

Result: The email forwards to: john.doe+john@gmail.com

Note: The alias field must not exceed 150 characters

Order of importance when matching an email

We evaluate alias matches in the following order of importance:

1. The exact match
2. The "Plus sign" match
3. The Regex match
4. The Wildcard or catch-all match *

Regardless of how many aliases an email matches, only the highest priority rule activates.

Example:

Given these aliases:

Even though contact@... matches multiple rules, the exact match i.e. "richard.hendricks@gmail.com" takes priority.

Example email matches based on the above configuration:

• contact@piedpiper.com → richard.hendricks@gmail.com – Exact match
• support@piedpiper.com → dinesh.chugtai+support@gmail.com – Regex match
• postmaster@piedpiper.com → gilfoyle+wildcard@gmail.com – Wildcard match
• contact+jared@piedpiper.com → richard.hendricks+jared@gmail.com – Plus sign match

The "plus sign" match

When an email is sent to an address with a plus sign (e.g., contact+label@piedpiper.com), ImprovMX:

• Matches it to the base alias (e.g., contact@piedpiper.com)
• Forwards to the configured destination (e.g., richard.hendricks@gmail.com)
• If the destination is a Gmail address, ImprovMX adds the same +label to the Gmail address

Example

Let's say you have the below forwarding setup:

Actual Email sent to: contact+newsletter@piedpiper.com

Final forwarded to: richard.hendricks+newsletter@gmail.com

ImprovMX strips the +newsletter when matching the alias, but re-applies it to the Gmail destination for consistency.

Note: Only works for @gmail.com and other domains below, not for G-Suite domains.

List of accepted domains for Regex plus sign forwarding

• gmail.com
• hey.com
• protonmail.com
• icloud.com
• fastmail.com
• outlook.com
• runbox.com
• yandex.com
• yandex.ru
• mailfence.com

If you have any questions about regex forwarding, feel free to contact us.