A single opt-in list means that as soon as a person subscribes to your list, they will be added and do not go through a verification process to check if their email address is valid.
• Helps to grow your list faster because a one-step sign up process is less hassle resulting in higher subscribe rates.
• Opens your subscriber list to collecting invalid, faulty and non-consenting email addresses. This can happen for a number of reasons including: errors made when entering emails, for example a typo that results in someone submitting an address that is not theirs and legitimate addresses being added by someone who does not own the address.
• Because of the reasons above your list quality is reduced, making it difficult to value metrics such as open rates and engagement levels.
• The risk of spam complaints is increased because you don't know if everyone on the list legitimately opted-in.
A double opt-in list means that when someone subscribes, they are sent a confirmation email with a link to follow to verify their email address, as well as to confirm that they did request to receive your correspondence. Only after the link in the confirmation email is followed will they be added to your list properly and be able to receive your campaigns.
• The double opt-in process ensures people are entering their information correctly which in turn equals a cleaner list.
• Reduces the probability of spam complaints because subscribers have had to take the extra step to confirm their consent. If spam complaints are recorded, you have a record of everyone's opt-in confirmation.
• Subscribers who 'say yes twice' are generally more responsive, meaning they're more likely to open emails and click links.
• Typically, up to 20% of initial subscribers will not complete the final confirmation step. Reasons include: people forgetting they subscribed and confirmation emails being deleted accidentally or getting stuck in spam filters.
• Potential subscribers who genuinely do want your newsletter may not understand the confirmation process and fail to click the link.