Imagine some of your contacts are no longer interested in your newsletters and want to unsubscribe. Either they use the 'Unsubscribe' option in the footer of your campaigns or inform you about their decision so you can mark them as unsubscribed.
But a few months later, their interest in receiving your newsletter is reignited and they want to be subscribed once more. How can this be handled in Zoho Campaigns? We will see in detail in this document.
Contacts can unsubscribe:
Themselves by clicking the Unsubscribe option in the footer of the email campaigns they receive (or)
You can use the Mark as unsubscribed option in your Zoho Campaigns organization to move them to the unsubscribed list yourselves
For your contacts to get resubscribed, they need to perform some actions at their end. This is important because they need to provide consent again that they're willing to receive campaigns again from you.
If a contact unsubscribes from your campaigns, that doesn't mean they are forever gone from your list. They may need your services again and look to resubscribe. As long as their needs are met, they can resubscribe.
There are a few ways in which contacts can resubscribe.
If a contact initially subscribed to your campaigns by entering their details (email and name) in a signup form created using Zoho Campaigns that you embedded in your website, they can access the website and sign up again. They need to know your website details to make use of the signup form.
2. From a past campaign
If your contact is unable to recall your website or even your email address to contact personally and request you to resubscribe them, they can instead access the most recent campaign you had sent them. Your contact should:
Navigate to their email inbox.
Search for the most recent email campaign they received from you.
At the footer of the campaign, they can click the Update your preferences option to open a new tab, select the topics that they're interested in, and click the Save Preference button.
They'll be resubscribed and added back as a Marketing contact in your Zoho Campaigns organization. What is the Update your preferences option?
Your contacts can see the Update your preferences option in the footer of the email campaigns. However, it will only be visible if the Contact Preference merge tag is used in your email campaigns. Otherwise, they'll just see the plain text version. The Contact Preference merge tag is a part of the Header and Footer merge tags. 
By default, the pre-designed templates will have this merge tag hyperlinked on the 'Update your preferences' text.
If you're using your own design, and would like to allow your contacts to resubscribe:
Select the desired text.
Click the Add link button in the toolbar that appears.
Click the Personalize drop-down in the pop-up window.
Choose the Header and Footer Merge Tags.
Click the Contact Preference merge tag and click Save.