There are occasions in which you collect email addresses from clients opting to receive your email marketing campaigns while being offline. Events or physical stores are good examples of such occasions. If you utilize such an offline subscription method it is important to always hold a copy of the form that the client used in order to subscribe to your newsletter, for safekeeping.
Keep in mind that offline collection can sometimes be tricky as it does not necessarily constitute proof of permission in case a member of your list later claims they never subscribed to it. Similarly, bad handwriting on a physical form means there are grounds for mistakes, and sending a campaign to a wrong or non-existent email address hurts both your sending reputation and the deliverability rates of your campaigns.
To avoid such issues we highly suggest that you create and embed a signup form on your site. It is very easy to create your own signup form with Moosend and it saves you the trouble of having to manually add new emails to your mailing list!