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Valid characters in email addresses or mailbox names
You can use these special characters in email addresses. Plus: Online test tools
Read here which special characters can be used in email addresses.
Table of Contents
The syntax
local part
These characters are part of an email address before the @ sign (i.e. left from @which is the local part):
- Letters A-Z and a-z (without accents and no umlauts, no ß)
- Digits 0-9
- The following Special characters:
! # $ % & ' * + - / = ? ^ _ ` . { | } ~
The following combination of characters is actually a valid email address in terms of syntax:
!#$%&'*+-/=?^_`.{|}~@example.comOr this email address is also valid:
-'-/-{@example.com(Source: Wikipedia)
The previous applies if the local part is NOT surrounded by quotation marks. In principle, however, the local part can also be enclosed in quotation marks, and then further characters are possible in the local part.
The following e-mail addresses may therefore also be valid:
".John.Doe"@example.com"John.Doe."@example.com"John..Doe"@example.com"John Doe"@example.com" "@example.org(space between the quotation marks)"john..doe"@example.org(points strung together)"very.(),:;[]\".VERY.\"very@\\ \"very\".unusual"@strange.example.com
However, it is not recommended to allow such mail addresses on the mail server (https://www.rfc-editor.org/rfc/rfc5321page 41). Thanks to the Commentator Maddse for the hint.
But now to the restrictions.
Please note that various special characters only appear in the before the @ the e-mail address (the local-part) are generally permitted. However, you may not necessarily be able to use all of these characters in the mailbox name on your own mail server. Which of the characters you can actually use for your mail address also depends on the configuration of the mail servers by the responsible administrators or the software used for this purpose.
domain part
For the domain (the part behind the @) other rules apply. Permitted characters in Domain names are: "a-z", "0-9" and "-" (hyphen). The minimum length of the domain name is 3 characters, the maximum length is 63 characters. The name may not begin or end with a hyphen. A valid domain name consists of a maximum of 63 characters. If you insist, you can also use ä,ö, or ü in the domain part, but I advise against this.
Does the e-mail address exist?
You can use the following online tools to check whether an email address is syntactically correct and whether it exists at all.
- https://www.experte.de/email-pruefen
- https://captainverify.com/de/mail-tester.html
- http://www.emailtester.de/tools/mailtester-emailadressen-checker.php
Secure email delivery
If you want to know how you can largely prevent someone from using your email address as the sender of spam emails, read this article about SPF, DKIM and DMARC.
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You can take an example from there.
Well done, thank you!
Two small things: There are now also .info extensions, so the whole thing should be extended. I would also be interested to know what this \. does? Maybe it's also possible to reply directly to my mail addy, as I rarely look in here.
@Michi: You're right, thanks for pointing that out. Has been corrected from {2,3} to {2,6} at the end of the long line. This means that .museum is now also recorded as valid.
\. means that a dot is really meant here, and not the dot as a regular expression symbol, where the dot (.) means that there can be (almost) any character in its place.
Excerpt from the Wikipedia article:
\ cancels the meta meaning of the next character if necessary. [...] In this way, a dot "." can also be searched for with "\.", while "\" is searched for with "\\".
http://de.wikipedia.org/wiki/Regul%C3%A4rer_Ausdruck
Hello,
yes, I saw that the post is already over 2 years old.
However, as the page can also be accessed in the future, it should also be updated.
I miss the German umlauts and all "ereg..." functions are marked as DEPRECATED since PHP 5.3.0.
There is a mistake in the regular expression: if you want to match a hyphen in a group [....], it must either be at the very end or escaped.
Thanks, I've corrected it (hopefully correctly).
The PHP regex extension filter_var can only be used if the email does not contain any special characters such as äöüÄÖÜ àéè etc..
I have read that no "." is allowed to the left and right of the @, but now after this explanation?
would be mustermann.@musterhausen.de a valid address?
Since dots are allowed in the local part, immediately to the left of @ yes.
Immediately to the right of the @ no, because no domain looks like that.
By the way, it is always possible that your provider has implemented its own rules for the creation of mailboxes ...
Moin,
It is not clear to me which characters may be used after the @ (to the right of the @).
Otherwise good presentation, you used pictures and spoke freely.
mfg Enrico
I've now made it clearer in the post. The domain name rules apply to everything after the @, and they have nothing to do with mailbox names (the one before the @). If you register a domain, you will certainly be prevented from entering characters that are not possible.
Simple, but unfortunately outdated and inadequate.
The possibility of quoted local parts, for example, is completely omitted. So " a \" valid em@il-N@me..."@domain.de is a valid email address. There are also far too many other restrictions in the article, with the result that email addresses that are actually valid are rejected.
See also: https://en.wikipedia.org/wiki/Email_address
The following is also very important there:
Common local-part semantics
According to RFC 5321 2.3.11 Mailbox and Address, "...the local-part MUST be interpreted and assigned semantics only by the host specified in the domain of the address." This means that no assumptions can be made about the meaning of the local-part of another mail server. It is entirely up to the configuration of the mail server.
One mistake above: neither the
'(single German quotation mark above), nor the'(apostrophe or single closing quotation mark) or the'(free-standing acute accent) are valid, but only the'and the`.So, the software has been removed from the
'a'made. What is meant is the one on the keyboard'("replacement character for the apostrophe").Thank you. I've also highlighted it as code in your comment so that it fits.