Can a look-alike domain swap letters that look the same?

Which letters get swapped?

( m → rn ) LATIN SMALL LETTER M → LATIN SMALL LETTER R, LATIN SMALL LETTER N

The Unicode list matches the small letter m to the pair r and n. It matches the digit 1 to the small letter l. It matches the digit 0 to the capital letter O.

So a name like yourfirm.example can become yourfirrn.example, and a name with an l in it can carry a 1 instead. In many fonts the change is hard to see in an email header.

Why do these swaps work?

The data in [ confusables ] provide a mechanism for determining when two strings are visually confusable.

The Unicode Consortium publishes this data as a way to decide when two strings are visually confusable. The edition we read is dated 6 August 2026.

Software can compare the two strings character by character. A busy reader compares them by eye, and the eye reads a word as a shape.

What can I do about letter swaps?

( 1 → l ) DIGIT ONE → LATIN SMALL LETTER L

1. List the swaps that fit your own name: m and rn, l and 1, o and 0.
2. Check whether those names are registered, and register the closest free ones yourself.
3. Read a sender's address letter by letter before you act on a payment request.
4. Zoom in on the address if a name looks right but the request is unusual.