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E-mail Addresses

E-mail addresses are used for routing messages. To communicate with other e-mail systems, Microsoft Exchange Server users must have an address that other systems can understand. Similarly, users in other systems must be represented by e-mail addresses in Microsoft Exchange Server. A user whose address is on another e-mail system but exists in the Microsoft Exchange Server directory is called a custom recipient. An e-mail address is the address by which Microsoft Exchange Server recipients (mailboxes, distribution lists, public folders, and custom recipients) are known to other mail systems.

Microsoft Exchange Server automatically generates X.400, Microsoft Mail for PC Networks, and Internet Simple Mail Transfer Protocol (SMTP) addresses for each recipient based on the directory name of the site and the organization. For example, the following are e-mail addresses for the user Maria Black, whose mailbox is in the NAmerica-W site in the FAB organization.

Address type E-mail address
X.400 address
g=Maria; s=Black; o=NAmerica-W; p=FAB; a=mci; c=us
MS Mail (PC)
Internet (SMTP)

If third-party gateways are installed, other addresses may also be generated. Gateways typically use the Alias Name field and other fields (such as the organization and site directory names) to generate e-mail addresses. Different gateways have different limits and restrictions for generating addresses.

X.400 Addresses

Microsoft Exchange Server supports X.400 addressing to enable direct communication with other X.400 messaging systems. The X.400 address identifies a Microsoft Exchange Server recipient in the global X.400 address space.

The following are the hierarchically-ordered attributes of an X.400 address:

Attribute Description
c Country (required)
a Administrative management domain, or ADMD (required)
p Private management domain, or PRMD (required)
o Organization
ou1, ou2, ou3, and ou4 Organizational units
cn Common name
q Generation qualifier
i Initials
s Surname (required)
g Given Name

For example, a valid X.400 address for Maria Black is:


The following characters are valid in an X.400 address.

Character Designation
A, B, ¼, Z Uppercase letters
a, b, ¼, z Lowercase letters
0, 1, ¼, 9 Digits
(space) Space
' Apostrophe
( Left parenthesis
) Right parenthesis
+ Plus sign
, Comma
- Hyphen
. Period
/ Forward slash
: Colon
= Equal sign
? Question mark

Microsoft Mail

If you connect to MS Mail (PC) or Microsoft Mail for AppleTalk Networks (also known as Quarterdeck Mail) systems, you can use a maximum of 10 characters for the Microsoft Mail network name, postoffice name, and mailbox name.


If you connect to the Internet or other SMTP systems, consider any character restrictions that SMTP imposes on its addressing scheme. In general, you can use lowercase and uppercase letters (a-z and A-Z; no distinction is made between lowercase and uppercase), numbers (0 - 9), and hyphens (-). Spaces are not allowed in SMTP addresses. Note that the default address is

Other E-mail Addresses

If you connect to foreign systems using third-party gateways, such as IBM Professional Office System (PROFS) and SNADS, consider the character restrictions. For example, PROFS and SNADS addresses usually contain only the uppercase letters (A-Z), numbers (0 - 9), and the following special characters: $, #, and @. When configuring recipients, restrict the characters that you use in the Alias Name field to the number allowed.