Are you wondering if email addresses are case sensitive? Is Office@ladedu.com the same address as office@ladedu.com? Find out here whether capitalization — uppercase and lowercase letters — does matter in an email address ⤓.
First, Faced Decaf in the Top Pot (after Pool Loop)
An emordnilap (or semordnilap, or semi-palindrome, it does not really matter what you call it) is a word that, read backwards, is a different word. Prominent examples of emordnilaps include the short “on” and the slightly longer “desserts” as well as “palindromes”, of course.
Put a word and its emordnilap back-to-back, however, and they form a palindrome — where it no longer matters whether you read the group forwards or backwards. Let’s say, you faced decaf in the top pot after your afternoon pool loop.
With that out of the way, does it matter whether you read an email address in capital or lower-case letters?
Does Capitalization Matter in an Email Address?
Technically yes: the user name part of an email address is case sensitive. In practice, most email services ignore case in email addresses, though, and treat all variants as the same address.
Their word: IETF include information on case-sensitivity of user names in RFC 5321.
In general, do not use capital letters or mixed case in email addresses. For all practical purposes, stick to only lowercase letters.
Which Part of an Email Address is Case Sensitive?
Email addresses consist of three parts (username @ domain), each of which has its own rules whether capital letters matter:
| Part of address | Case sensitive | Practical reality |
|---|---|---|
| Username | Technically yes | Usually not case sensitive |
| @ | no | Single symbol |
| Domain | no | Always treated as lowercase |
While capitals never matter for an email address’s domain part, the username (what precedes @) is, in theory and according to the email standards, case sensitive.
Case lowered and closed?
Tips help fuel these email and tech how-tos.
Capitalization in Email Address Example
This means
eXamPle@ladedu.comtechnically is a different address fromeXampLe@ladedu.comwhileeXample@Ladedu.comis the same address aseXample@ladedu.com.
At the same time, the following is true:
- Just about all email services treat the two addresses above (and all other mixed-case variations) as denoting the same email account.
- Practically every email user will expect capitals not to matter in an email address.
Therefore, you should not use mixed case yourself but use only lower case in the username part of your email address.
Where capitalization might matter: Best Headline Capitalization Tools
Does Capitalization Matter in an Email Address: FAQ
Can I use small caps or other alternative capital letters?
No.
In email addresses, it is usually best to only use (lower-case) ASCII letters a–z (ASCII 97–122).
Do not use Unicode characters that mimic upper case or small caps (such as ᴇⅹᴀмᴘʟᴇ@ladedu.com).
(First published April 2020, last updated March 2026)