Key Takeaways

  • The domain is never case-sensitive. RFC 5321 says domains follow DNS rules, so Example.com and example.com are the same.
  • The name before the @ can be, on paper. The standard lets the receiving mail server decide, but it also says relying on case hurts interoperability and is discouraged.
  • Google stores usernames in lowercase. Gmail usernames use only the letters a to z, and Google Workspace converts uppercase to lowercase when a username is created.
  • Your CRM is where case causes trouble. The same person typed two ways can become two contacts. Store addresses in lowercase on import and in forms.

Contents

  1. What the email standard says
  2. What Gmail and Google Workspace do
  3. What is case-sensitive
  4. What this means for sales and support teams
  5. Keeping addresses clean in a CRM
  6. FAQ

Under the email standard, the part of an address before the @ may be case-sensitive and the domain after the @ is not. In practice, mail systems are told not to rely on case, and Google only stores lowercase usernames, so Name@Example.com and name@example.com normally reach the same inbox. The place case still causes real problems is your own contact list. Every rule below comes from the standard or the provider’s own pages, checked on November 8, 2026.

What the email standard says

Email delivery runs on SMTP, defined in RFC 5321. An address has two parts: the local-part before the @ (the mailbox name) and the domain after it.

Section 2.4 of RFC 5321 treats them differently:

  • The domain is not case-sensitive. The RFC says mailbox domains “follow normal DNS rules and are hence not case sensitive.” GMAIL.COM, Gmail.com and gmail.com are one domain.
  • The local-part must be treated as case-sensitive by the systems passing it along. Mail servers in the middle have to preserve the capitalization exactly as typed. They can’t lowercase it on the way through.
  • Only the receiving server decides what the name means. Section 2.3.11 says the local-part is interpreted only by the host named in the domain. So whether “Name” and “name” are the same mailbox is up to the provider that hosts the address.
  • Relying on case is discouraged. The same section adds that exploiting case in local-parts impedes interoperability. In plain terms, a provider could create two mailboxes that differ only by case, but the standard tells it not to.

That is why the honest answer has two halves. Technically, the name part can be case-sensitive. In practice, providers avoid it, because people type addresses however they like.

What Gmail and Google Workspace do

Google’s help pages spell out the rules for its own usernames.

  • Gmail usernames use lowercase letters only. Google’s “Create a username” page says usernames can contain letters a to z, numbers 0 to 9 and periods. There is no capitalized version of a Gmail address for mail to go to.
  • Google Workspace converts uppercase to lowercase. Google’s name guidelines for Workspace users say usernames must be lowercase, and uppercase letters entered when a username is created are converted to lowercase.
  • Dots don’t matter in Gmail, but they do at work. Google says mail sent to any dotted version of a Gmail address goes to the same person. For work or school accounts, dots do change the address.

For other providers, we didn’t find an official page that states the rule, so we won’t name one here. If an address matters, send a test to it with different capitalization and see if it arrives.

What is case-sensitive

People mix up the address with the things around it. Here is what does care about capitalization:

  • Passwords. Microsoft’s support page on protecting Word documents says passwords are case-sensitive. Check Caps Lock before you assume a sign-in is broken.
  • Parts of web links. RFC 3986, the standard for web addresses, says the scheme (https) and the host name are case-insensitive. The other parts, such as the path after the domain, are assumed to be case-sensitive unless the scheme says otherwise. So a link in your email footer can break if someone retypes its path with different capitals.

And here is something people expect to be different, but usually isn’t:

  • Plus-address tags. Plus addressing adds a tag after a plus sign, like sean+newsletter@contoso.com. Google says mail to your address or any plus variation arrives in your inbox. Microsoft says plus addressing is on by default in Exchange Online, and if the full tagged address doesn’t match a mailbox, Exchange tries again without the tag. So the tag is a label for filtering, not a separate mailbox.

What this means for sales and support teams

Delivery is rarely the problem. Your own records are. Many databases and spreadsheets compare text exactly, so “Dana.Lee@Acme.com” and “dana.lee@acme.com” look like two different people unless something tells them otherwise.

That causes a few common issues:

  • Duplicate contacts. A lead fills out a web form in one case, then a rep types the address from a business card in another. Now you have two records and two histories.
  • Double sends. A campaign goes to both records, so the same person gets the same email twice. That annoys people and invites spam complaints.
  • Missed unsubscribes. If someone opts out on one record and the duplicate stays subscribed, you keep mailing a person who asked you to stop.
  • Split reporting. Calls, emails and deals spread across two records, so nobody sees the whole picture.

The fix is simple. Pick one format and stick to it:

  1. Lowercase on import. Before you load a spreadsheet, convert the email column to lowercase and trim spaces. Then remove duplicates.
  2. Lowercase in forms. Have your web forms or form plugin store the address in lowercase when it’s submitted.
  3. Match without case. When you check if a contact exists, compare lowercase to lowercase.
  4. Leave the display alone if you like. You can still show “Dana Lee” with capitals. Only the address field needs one standard form.

Clean addresses also help deliverability. Bounces and complaints hurt your sender reputation, and duplicates add to both. Our email deliverability guide covers SPF, DKIM, DMARC and list hygiene in plain English.

Keeping addresses clean in a CRM

A CRM is only as useful as its records. One person should be one contact, with every email, call and note in one place. If you’re setting up a contact list from scratch, our guide to what a CRM database is explains how contacts, companies and deals fit together, and the CRM lead management guide covers how leads move from first form to closed deal.

In Conduyt, replies land on the contact’s timeline once reply capture is set up, next to calls and texts, which is one more reason to keep each person on a single record. Conduyt is a flat monthly rate with unlimited users and contacts, and the 20-day trial needs no credit card. See pricing.

Before you send, run the message through our free email spam checker to catch wording that filters flag. And make sure your sign-off is text, not one big image, with the free email signature generator.

Frequently asked questions

Are email addresses case sensitive?

Partly, on paper. Under RFC 5321 the domain after the @ is never case-sensitive. The name before the @ may be, because the receiving server decides what it means, but the standard discourages relying on case. In practice, capitalization rarely changes where mail goes, and Google stores Gmail and Workspace usernames in lowercase only.

Is Gmail case sensitive?

No capitalized Gmail address exists to send to. Google’s help pages say Gmail usernames can contain only the letters a to z, numbers and periods, and Google Workspace converts uppercase letters to lowercase when a username is created. Dots are ignored in personal Gmail addresses but do count for work or school accounts.

Does capitalization matter when I type an email address?

Not for the domain, which RFC 5321 says follows DNS rules and is not case-sensitive. For the name part, the receiving provider decides, and the standard tells providers not to depend on case. If one address really matters, send a short test with different capitals and confirm it arrives.

Should I store email addresses in lowercase?

Yes, for contact lists and CRMs. Many databases compare text exactly, so the same address typed with different capitals can become two contacts. That leads to double sends, missed unsubscribes and split history. Convert addresses to lowercase on import and in web forms, then match new entries against the lowercase version.

Are plus addresses like name+tag@ different inboxes?

Usually not. Google says mail to your address or any plus variation arrives in your current inbox. Microsoft says plus addressing is on by default in Exchange Online, and if the tagged address doesn’t match a mailbox, Exchange retries without the tag. The tag works as a label you can filter on.

Sources

Checked on November 8, 2026. Provider rules change, so test with your own provider if an address matters.