Adding/Editing Reminders

You can add a new reminder to currently displayed issue in 3 ways:

By using 'r', keyboard shortcut
By selecting "Add New Reminder"
By pressing "Add New Reminder" link in the Reminders right issue panel

All of these options display "Add New Reminder" dialog shown below:

Summary	Summary of the Reminder, this is shown on the email message body by default email template.
Relative To	A reminder may be send on a specific day or specified hours before a date field of the issue, like due date.
Date/Time	Only shown "Relative To" field is set to None. Reminder email is send on selected date and time.Due to mail queue in and performance optimization there may be a few minutes delay.
Hours Before	Only shown a specific date field is chosen from "Relative To" field. Reminder email is send relative to selected "Relative To" field. For example if "Due Date" is chosen and "Hours Before" field is set to 48, reminder email is send 2 days before due date.
Period	Period can be daily, weekly, monthly or a Cron expression. If you select Cron Expression you also need to provide a valid cron expression in the corresponding field.
Cron Expression	Only valid if period field is set to Cron Expression. See corresponding tutorial on cron expressions and samples.
User	Select the users who will be notified with the email. You can select multiple users here. In addition to normal users, you can also specify following pseudo users: Assignee Reporter Watchers Commenters Voters These pseudo users are dynamic and their corresponding user will be determined when the reminder is triggered. For example if you select assignee instead of current username of assignee and the assignee changes before the reminder is delivered in the future, the reminder will be delivered to new assignee of the issue.
Email	You can write email of any 3rd party which don't have JIRA account. You can disable sending e-mail to "E-mail addresses" from add-on settings.
Project Role	Role you want to notify for the project of the issue. You can disable sending e-mail to "Project Roles" from add-on settings.
Group	The User group you like to send reminder to. Note that there may be a lot of users in a group and it may overload your JIRA or mail server if you are not careful. You can disable sending e-mail to "Groups" from add-on settings.
Description	Description of the reminder. This is used in mail body of default email template. You can use wiki markup inside description. This markup will be converted to HTML before sending email. You can preview markup using the preview button on the bottom left hand side of description field.
Private	Private reminders are only visible to you. Use this if you are using sensitive information in reminder summary or description.

You have to select at least one reminder target, enter a summary information and a reminder date. Reminder date should be at least 5 minutes ahead of current time. Summary could be maximum 250 characters long and description could be maximum 5000 characters long. If you enter multiple targets all of them will receive notification. If a user matches more than one target, he will receive notification only once. You cannot use rich text in summary and description fields, they all need to be in free text format. For security reasons HTML content is also escaped and will be displayed as plain text.

Each time a reminder is send a comment may also be created depending on add-on settings. Even if you delete the reminder you can check issue comments to see when a reminder is send.