What’s in an eMail Address?

When you are deduping, consolidating or doing identity resolution with party master data the elements that may be used includes names, postal addresses and places, phone numbers, national ID’s and eMail addresses.

Types of eMail addresses

In this post I will look closer into eMail addresses based on a general list of types of party master data.

You may divide eMail addresses into these types:


This is a private eMail address belonging to an individual person.

Typical formats are myname@hotmail.com and nickname@gmail.com and name123@anymail.com

You may change your eMail address as a private person as time goes or have several such addresses at a time depending on your favourite providers of eMail services and other reasons to split your personality.


A household/family may choose to have a shared eMail Address for private use.

Typical format will be xyz-family@anymail.com where the word family of course could be in a lot of different languages like famiglia-italiano@email.it

A special usage is the GROUP where two (or more) names are included like mary-and-john@anymail.com


This is the eMail address you are assigned as an employee (including owner) at a company.

Common formats are abc@company.com and name.name@company.com

When you change employer you also change eMail address and you may have several employers or other assignments at the same time. Also different formats like initials and full name may point to the same inbox.


Here the eMail address is not pointed at a particular person but some sort of a team within a company.

Formats are like sales@company.com and salg@firma.dk and vertrieb@firma.de choosing the sales team in some different languages.

Some eMail are referring to a specific FUNCTION like webmaster@company.com


This is an eMail address for the entire company.

Most common formats are info@company.com and company@company.com


Often a field designed for an eMail address is populated with invalid values going from obvious wrong values like XXX to harder detectable syntax errors and not existing domains.

Real world duplication

Many online services are based on registration via an eMail address assuming that one eMail represents one real world entity which of course is not the case.

Even on a service like LinkedIn where you may attach several eMail addresses to one profile you do encounter persons with obvious duplicate profiles.

Multi-channel marketing and sales

An increasing number of organisations are doing both offline and online operations today and when building enterprise wide master data hubs the eMail address becomes an more and more important element in matching party master data.

In such matching activities the eMail address can not stand alone but must be combined with the other elements as names, postal addresses, phone numbers and national ID’s upon availability.

Success in automating such processes is based on advanced algorithms in flexible and configurable solutions.

Comment or eMail me

If you also have been battling here I will be glad to have your comments here or by mail. My mail is hlsgr@mail.tele.dk and hls@omikron.net and hls@locus.dk and hls@dmpartner.dk and nordic@omikron.net

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11 thoughts on “What’s in an eMail Address?

  1. Jim Harris 28th November 2009 / 17:17

    Excellent post Henrik,

    I see e-mail address overtaking other contact types (e.g., telephone numbers) for preferred master data attributes for preferred communication method and possibly even for simple identification purposes (however, like you, I am also not suggesting it as a stand-alone “key” attribute in any system).

    As you noted, an increasing number of organizations are doing online operations. Additionally, an increasing number of consumers are using e-commerce to make their purchases, and one of the most common user name or account name formats in e-commerce is e-mail address.

    As you also noted, people typically have multiple e-mail addresses, change them more frequently than other attributes (e.g., names and postal addresses), and often validly maintain multiple e-mail accounts at the same time.

    For example, I buy most of my books and small electronics online. I use my “work” e-mail address for purchases that I typically deduct as business expenses and one of my “personal” e-mail addresses for making non-deductible or other purchases.

    Therefore, some of my online vendors would view what appear to be duplicate accounts – every other attribute except for e-mail address is the same. However, it would be a mistake for these vendors to “consolidate my duplicates.”



  2. Henrik Liliendahl Sørensen 28th November 2009 / 17:50

    Thanks for e-commenting Jim.

    Your example as being both a small business owner and a consumer is actually very common as around 80% of all enterprises are one man bands (statistics may very a bit between countries).

    As you say, those having you and your enterprise as a customer should not merge your accounts but rather link your accounts in order to have a complete customer behaviour view and go for a larger share of your wallet (sorry, that’s business life).

    All the e-best


  3. Rich Murnane 30th November 2009 / 14:17

    Very nice posting Henrik,

    My organization uses email addresses frequently to try to identify “people” in transactional data. Once identified, we assign the transaction to that person’s database record so we can have illustrate all transactions for that person.

    Upon arrival in 2006, I found some of our systems to be using email address alone as the matching criteria. As you can guess we found this to be very troublesome due to the types of emails you mention above. Your comment about “In such matching activities the eMail address can not stand alone but must be combined with the other elements as names” is spot on. After battling data quality issues due to this matching by email only we’ve since changed these systems to matching transactions to people by using the combination of email and their last name. Although not perfect, this change which works very well for our particular business as it would be uncommon at best for us to have to match two distinct people who are sharing the same email address and have the same last name. We of course also allow a person to have >1 email address – which had to be built into the system as it was originally modeled to be a one to one relationship.

    Another type of email address we find quite often would be the “Administrative Assistant” email address (aka Admin). We often find forms are filled out by an Admin for executives and as such the Admin uses their own email address but the contact information of the Senior Executive. We originally thought this was an anomaly and we not concerned too much about it but as time progressed we found this happening more often and more often. Funny thing is though, my wife did some online ordering recently in my name (and credit card info) and used her email address – essentially the same situation. I would however stand clear of calling my wife my “Admin”, it’s more likely the other way around (I wonder how that would really be “modeled”?).

    Thanks for posting this and best regards.

    Rich Murnane

  4. Julian Schwarzenbach 30th November 2009 / 14:41

    Another type of email address is the NO REPLY address typically used by companies to provide notification to customers/subscribers, but where there is no facility to reply.
    Most of these addresses relate to businesses and tend to be in the format messages-noreply@company.com or similar. They are often fixed addresses which allows them to be added to white lists to prevent them being falsely marked as spam.

    Yet another different, but related, example includes the semi randomised addresses often used to send out web notifications and newsletters. These will typically have a string of digits/characters in the first part of the address and be sent to single recipients only. Again, they typically cannot be replied to, but may use a fixed string of characters for each subscriber.

  5. Karen Lopez 30th November 2009 / 15:03

    Great discussion. I try to remind team members that addresses are addresses for inboxes, not people. I’d also add some other types of addresses:

    Time-limited disposable e-mail addresses. Provided by a service in either an attempt to avoid further contact or to avoid matching other contacts.

    Aliases: E-mail addresses that don’t exist as mailboxes, but act as forwarding addresses to other inboxes.

  6. Henrik Liliendahl Sørensen 30th November 2009 / 18:13

    Thanks Per, Rich, Julian and Karen.

    How to model the ‘Admin’ type of eMail is a good question. As with all modelling it’s a compromise between picturing the real world construct and the business need – basically either a relation between two EMPLOYEE (type of eMail addresses) or a HOUSEHOLD relation I think.

    As for the NO REPLY eMail it’s really not a type of eMail you want to see in a CRM or SCM context – really something you should mark at the level of INVALID for these purposes.

    The time limited types of eMail addresses is sure a symptom of “the customer fights back” when we as a business try to learn about our customers. If only they knew about our good intensions 🙂

  7. wesharp 1st December 2009 / 17:19

    This post touched a nerve close to the heart. I battle the perceived uniqueness of email addresses on a project to project basis. As Karen also pointed out email addresses are inboxes not people. What further compounds the issue in the last category of invalid email addresses.
    I’d love to see a follow up post with details on how you treat that category. Not so much the ‘XXX” entries but the invalid domain names and so forth.

  8. Henrik Liliendahl Sørensen 1st December 2009 / 18:24

    Thanks William.

    There are plenty of services out there for verifying syntax of eMail addresses plus also whether the domain is in use. I use a method in the Omikron Data Quality server for that when needed.

  9. Marvin Willis 11th December 2009 / 18:44

    You have great information on e-mail addresses, but I have even a different problem. Presently, I use first names and domain name for my e-mail address. Now my business is almost sold and I would like to set-up all e-mail addresses on departments but at the same time not lose any e-mails that may be addressed to me, for example. I think this would mean forwarding in my server. For example. setup Adm@windcoflags.com and forward marv@windcoflags.com to adm@windcoflags.com etc Does it make sense?

    Please comment.

  10. Henrik Liliendahl Sørensen 13th December 2009 / 04:38

    Hi Marvin, thanks for commenting on my blog. I’m not the expert on eMail administration, but I guess what you suggest is pretty normal.

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