I'm designing a flyer which has an email address on it.

Is it necessary for me to have the email address in lower case?

Or can I have it in upper case to put more emphasis?

I did my research on the net but all results seem to relate to the email addresses itself, not as it may appear on a flyer.

My client doesn't seem to like the idea of having it in upper case.

  • 13
    If your client doesn't like it.. that should be enough reason not to do it. I wouldn't stand my ground on such a matter with any client. it wouldn't be that important to me.
    – Scott
    May 22, 2018 at 10:02
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    Remember that email addresses are case sensitive by default
    – Ferrybig
    May 22, 2018 at 16:29
  • 1
    @Ferrybig brings up an important point: the internet can be case sensitive. No matter what is decide, test the email address using the exact case shown to be sure it will get through.
    – Yorik
    May 22, 2018 at 16:33
  • 4
    @1171111 Read the official smtp specification: "The local-part of a mailbox MUST BE treated as case sensitive", hence can be said that email addresses (are partly) case sensitive by default. That most people make them case insensitive on their own server is a totally different matter
    – Ferrybig
    May 22, 2018 at 18:45
  • 6
    @Ferrybig: The specification requires that any entity which transports a message must deliver it the same combination of upper and lower case as used by the sender, which makes such transport agents case-sensitive. The final disposition of the message is up to the recipient. If the final host that receives a message wants to treat fredjones, FredJones, FREDJONES, and even BarneyRubble as identifying the same mailbox, it would be free to do so. If it wants to treat that as four different mail boxes, that would be allowed too.
    – supercat
    May 22, 2018 at 19:24

7 Answers 7


Clients have the final say. Even if you disagree with it.

Disregarding that there maybe technical reasons why uppercase is a bad idea. And disregarding the fact that upper case lowers readability and often has the opposite effect of "emphasis"... Client direction is always the deciding factor.

If the client doesn't like it, don't do it.

If you are designing something and the client asks you to change an aspect, then by all means explain why you think they way you have it is better in your opinion. However, if the client still wants things change, then change them. The client is paying you for services, therefore they have the final word.

  • The case of an email address has no technical bearing.
    – Carl
    May 22, 2018 at 20:08
  • 3
    @Carl unless the email server rejects unknown emails due to case sensitivity. [email protected] is not the same as [email protected] to some mail servers. it's rare, yes. But it is not impossible.
    – Scott
    May 22, 2018 at 20:12
  • true though in the opposite case where the client wanted the email address in all caps, it could be trivially tested whether or not this was fine
    – OGHaza
    May 23, 2018 at 2:20
  • 2
    There's no "bad" or "good" ideas when it comes to email addresses, there's basically just the specs, which state that the part before the @ can be whatever the server wants (including being case-sensitive) and that the part after the @ is always case-insensitive, because that's the domain.
    – emmalyx
    May 23, 2018 at 7:43


Sorry for that.

As commented by others, while the user name in an email address is case-insensitive, the domain name is not. In some extreme cases, YouCouldUseCamelCase use of capitals. They are used on long words. But choosing a long word as the first part of a public email is also a bad idea.

Sometimes could be necessary for a domain name. FreeDomainNames.Example.com

The truth is that you should drop the idea now. Even in the comments, you have the idea fixed in your mind even after technical arguments

I'm sorry but this relates to a flyer I'm designing.

No, you are not designing your cell phone cover where you can use unicorns if you want.

You are potentially confusing customers, potentially preventing an email to arrive and messing around with the client that also do not like it. There is no single argument to keep thinking about it.

Change size, change the font, change thickness, change weight, change the kerning, put an outline, put a bullet, put an icon, put an explosion, put a hologram... you have options.

There could be some argument if the client wanted to do that. But this is not the case.

  • 3
    The statement "an email address is case-insensitive" is generally, but not universally, true. The domain-name part is required to be case-insensitive, and many email hosts make the local part case-insensitive, but they are not required to do so. May 22, 2018 at 22:28
  • That is why I pointed "the domain name is". I'll edit that.
    – Rafael
    May 23, 2018 at 0:16
  • @Rafael I’ve just suggested an edit to the sentence in question since it was still quite unclear and misleading. Sep 15, 2019 at 13:35

bigger, bolder == more noticeable, more legible.

ALLCAPS == shouting & actually harder to read.

I sometimes use title case on mine, TxxxxxMedia, which makes it slightly easier to read & my mail server doesn't mind it.

Late edit
According to the other, later, answers here, no server should mind any type of case differentiation in the domain name, only potentially in the part before the @, so camelCase or TitleCase is fine.

  • Yeah but this i really dependent on the server. Staging a test shoiuldnt be sop hard though.
    – joojaa
    May 22, 2018 at 10:50
  • 1
    "ALLCAPS == shouting" I couldn't agree more but I have seen fonts which are basically all caps yet somehow manage to not come across as shout-y.
    – MonkeyZeus
    May 23, 2018 at 12:54

The mail standard says that what is before the @ could be case-sensitive and is under control of the host system, and what is after @ is case insensitive as it is under the control of the mail delivery system.

In practice the prefix is very rarely considered as case sensitive (I've never encountered any such system), so you can use any casing you want and that will work with very very high probability. My official address is something like [email protected] and I always present it as [email protected]; I've never had any problem for more than 25 years...

  • 3
    I have encountered systems that actually cared. Its rare but you can make it care. But the ive seen systems that didn't care what you typed in the dotted portion before your username too.
    – joojaa
    May 22, 2018 at 15:08
  • It's not really that convincing to give just one example of an email address that works in a case-insensitive way: there's no doubt that they exist, but it's no proof that the opposite doesn't exist too :)
    – psmears
    May 22, 2018 at 22:20
  • @psmears Of course as it is permitted, but it is fairly rare and strongly discouraged to do so. May 22, 2018 at 22:38
  • 1
    Your one server has never cared. This says nothing about whether someone else's server will care or not. However, it's easy enough to test. Send an email to [email protected] and see if it arrives. If so, that receiving address will work for everyone.
    – CJ Dennis
    May 23, 2018 at 2:33
  • @CJDennis I had several address from many different providers (GAFA and alike, private companies, public institutes, private servers etc), I've never experimented case problem with mail. mail server softwares are not so numerous and almost every admin use one of the three or four available and almost use the same kind of configuration (which doesn't care about case). May 23, 2018 at 4:56

Depends on the mail system. Many mail systems do not actually care, but they could be configured to care. Some systems also allow you to have extra stuff in mail addresses, ask your mail provider for documentation.

  • I'm sorry but this relates to a flyer I'm designing. Thanks anyways.
    – Bjorn Liza
    May 22, 2018 at 10:47
  • 4
    @BjornLiza If you dont know then you can not change.
    – joojaa
    May 22, 2018 at 10:49

As the designer you may show the best design solution to your client, along with what they asked for, to allow them the greatest choice.

Is this a printed flyer? If so, emphasize the email address the best way so people can read it easily and remember it.

If it's a long complicated address then you should style it to distinguish the words from each other.

The letters all need to be run together with no spaces.

Sentence case, with the first letter of each word capitalized, is supposed to be most legible.

I personally disagree with adding periods between the words, but's that's a choice before the "@" symbol.

The ".com" can be de-emphasized, minimized, or omitted if it's a common one like gmail.

If it's a digital flyer and the email link must work and be clickable, all the same rules apply because html and css allow a link to be disguised as something other than a full text version of the email address.

Style your email address text the best way you see fit, respecting your client's wishes, perhaps add a graphic like an email icon, and make the whole thing the active email link.

  • On a printed flyer, never remove any part of an email address. You cannot just remove the .com bit of a Gmail address and expect people to get it – they won’t. They’ll send an email to yourname@gmail and be frustrated and angry when it doesn’t arrive. Adding periods between words is also obviously not going to work for creating a flyer with an existing email address – that is an option when setting up an email account, not when typing an existing one out on a design. Sentence case is, as others have said, potentially risky and destructive and also just looks bad. Sep 15, 2019 at 13:32

Don’t add a pointless layer to something so simple. Email addresses are lowercase because that’s the way the are. Don’t have people thinking the have to make an extra effort to hold an extra key down when they don’t. Use the KISS approach (“keep it simple, stupid”; not directed at you).

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