There are occasions when the parameters on which you need to segment a List are such that human intervention is required.
For example, you have ten Subscribers in a List that missed out on a Campaign for whatever reason, and you now want to send it to them. There is no particular logic to which Subscribers they are, but YOU know which they are. Alternatively, there are a few Subscribers in one of your Lists that YOU want to send specific information to, based on YOUR judgement of just which they are. Both scenarios require your intervention to identify those to receive the communication.
This is achieved, for any List, by adding a Custom Field maybe called "Mail To" with a Tag MAILTO.
That field can then have a "Value" added that can be "Searched" on to create a "Segment". This is easily set up as below, starting by creating the Custom Field.
Now create a Segment based on a value in that Field.
In "Subscriber" view Edit the relevant Subscriber Records and add the value 1 in the "Mail To" field.
So now two Subscribers have been identified by adding a "value" of 1 that a Segment can "Search" on.
And in the relevant Campaign Setup by selecting the List and the Segment we see that there are 2 subscribers that the Campaign will be sent to.
The reason we suggest using 1 as the "value" as against the maybe more obvious "Yes" is that you can use the function over and over again by using 2 as the next Value, and 3 etc., and just update the Segment to look for the higher "value". By using that technique you do not have to keep going back through Subscriber Records to delete the previous values as one would have to do if you used "Yes".