E-mail address Structures:

In a company like SITA people can have several addresses. For example, I have at least 4 different ones:
SMTPDries.Bessels@SITA.INT. SMTP address often follow this format but other formats are possible like driesbessels@yahoo.co.uk or dries.bessels@sitatex.sita.int
Type-BAMSABXS
X400G=dries/S=bessels/O=SITA/P=sitatex/A=SITAMAIL/C=WW
Lotus NotesDries Bessels/Amsterdam/SITA/WW

One other often used format is AFTN, an example of such an address is EHAMOKLM.

Below is a table showing the equivalencies in these addresses:
  givenname surnameIATA codeICAO codeorganizational
unit or
department
organization
or company
ADMD (1)PRMD (2)Country or Top Level
Domain
Type-B     AMS  AB XS     
SMTP dries bessels     SITA    INT
X400(4) dries bessels     SITA SITAMAILSITATEXWW
Notes dries bessels      AmsterdamSITA   WW
AFTN       EHAM O KLM    

  • (1) x400 only : administration management domain for example a local PTT or network like SITA containing several PRMD's.
  • (2) x400 only : private management domain or company internal domain.
  • (3) This EHAM could be seen as an abbreviation for Europe/Holland/AMsterdam although this is not valid for all AFTN addresses.
  • (4) X400 is sometimes referred to as the bureaucrats dream. Where a Type-B address consists of only 3 attributes X400 has at least 27 attributes. Luckily there is no need to use them all but they are available if you want to use them!

When sending a message to another domain, for example from Type-B to SMTP the address has to be converted in the gateway. This conversion can happen in two ways, either via a table or via mapping.

When done via a table the system has to be preconfigured with all possible addresses. The gateway will receive a message for AMSABXS and will send it to DRIES.BESSELS@SITA.INT. If it receives a message for an unknown address it will have to reject the message.
Maintenance for this kind of conversion can become very cumbersome and the tables can rapidly become very large!

The alternative is to use address mapping. With address mapping no specific address is known, it is rule based so much easier to maintain.

A number of example mappings are:
SMTP <-> Type-B
AMSABXS@TYPEB.SITA.INT<-> AMSABXS

SMTP <-> Lotus Notes
Dries.bessels@sita.int <-> dries bessels
In the Lotus Notes address book names like 'Martijn van de Staak' are valid. Names like this are transformed into Martijn.van_de_staak@sita.int.

Almost all other mappings are done via a one-by-one mapping. These have to be manually entered in the configuration of the relevant tables. Some examples are:
Type-B <-> X400
HAGSXXS <-> G=Dries/S=Bessels/O=SITA/ADMD=Sitamail
/PRMD=Sitatex/C=ww
 
TYPE-B <-> AFTN
AMSTOKL <-> EHAMOKLM
 
TYPE_B <-> X400 <-> SMTP
AMSTOKL <-> PRMD=GW/ADMD-Sitamail/C=ww/DD.rfc-822=telex@klm.nl
The DD-RFC indicates here that it is an extra attribute indicating it is not a real X400 addres but in this case an SMTP address. Therefore the message is sent from Type-B to an X400 system which in turns sends it to an SMTP address.

If mapping for whatever reason is not a viable option or if the message to be sent is a one-off message you can use 'in-body adressing' instead of mapping. This means that you send the message to the address of the gateway and add a special line in the message indicating what the gateway should do with that. This is often used for Bfax but also for AFTN and many other systems.

In-body addressing demands a reasonable amount of knowledge and understanding from the user and therefore should be avoided if possible.

The simplest is a fax sent from a Type-B system:

QU HDQFAXS
.AMSABXS 123456
FAX 31204654738
text
text

This message gets delivered over Type-B to HDQFAXS which is the FAX gateway. The FAX gateway then looks in the first line to see if it finds the identifier FAX with a number there. If that is there it will then proceed to dial the number(s) behind the word FAX.

An other example of this is to send a message from a Type-B station to an SMTP address using 'in-body addressing':

QU JAOGWXS
.AMSABXS 1234546
to driesbessels@yahoo.co.uk
text
text

This message gets delivered to the internet gateway (JAOGWXS) which will then proceed to send it to the SMTP address.



For any questions or comments please do not hesitate to contact me via E-mail