Contact Custom tags are those, that the user defines according to his needs from a list of contact fields and the custom field data. This gives you the liberty to use more number of fields than just the usual email, first name and last name.
User defined tags allow you to choose either of the two fields:
Pre-defined fields are fields set by default which are basic contact info in the sign up form / add contact page. Fields like contact email, first name, last name, company name, phone and etc.
Decide on a field you want to address your subscribers with, define the tag, your mail default value and social default value. There are no tags that are defined by default in this case. You’ve the freedom to define your own tag for your own understanding, reference and easy usability.
User defined fields are fields that can be used to address your subscribers, only if you've created a custom field. If you’ve, then select the field and define the tag, your mail default value and social default value.
Having said on what merge tags are all about, we will now, guide you on how to easily use these tags to make your campaigning experience neat.
The flow of using these tags in your content is pretty much the same, except that you need to create a set of tags.
Please note that, during campaign creation, in the text editor, selecting a user defined field at the drop down menu will be possible only if you’ve created a custom field. Learn more on how to create a custom field for a mailing list
For e.g., If you want to address your subscribers with their secondary email address copy, paste the tag in your content $[UD:SEC]$ or $[UD:SEC|ABC|CBA]$