The most probable cause is using incorrect e-mail addresses. To check them, go to MODERATION / Shop contact details / "e-mail addresses" section. If they are correct, report a ticket with a problem description to server administrators.
Yes. Start with deciding on what information you would like to send in e-mail and to whom. To select an adequate group of customers (e.g. customers with registered account but never bought anything, only wholesalers etc.) go to CUSTOMERS / Customer analysis (CRM). There you will find a list of available search options. After clicking on Search a list of customers will be displayed. Select the ones you want to send a newsletter to with checkboxes and click on Send newsletter. Another step is newsletter sending form - it allows to enter message contents, subject etc.
Soft bounce is a temporary issue with an email delivery. Its most frequent cause is customer's mailbox overstock or short breaks of the Internet connection.
Hard bounce means that it is not possible to deliver a message to a particular email address and it will not be available in the future either. The most frequent cause of a hard bounce is a spelling mistake in the email address or deleting the account by a user.
CTR (Click Through Rate) is the ratio of clicks to the number of sent messages.
OR (Open Rate) indicates how many times a message is opened. It is the ratio of messages displayed by a receiver to the number of sent messages.
If a newsletter has not been sent to all the recipients of the campaign, you can resume its mailing. In order to do it go to MARKETING > E-mail and SMS newsletters > Sent e-mail newsletters statistics and click on the name of a campaign. If there is no "Resume sending" button the newsletter has been sent successfully to all the recipients.