The way you approach unsubscribing depends on the "category" of the email you want to stop receiving. It's worth noting that some emails cannot be disabled.
Emails at Toggl Track fall into one of these three categories:
Reports, alerts, and other
Core service emails (can't be turned off)
Emails in this category include periodic newsletters about stuff that's been happening at Track. They often mention upcoming features and offers you might be interested in. To unsubscribe from these emails click on the Unsubscribe link inside the actual email or visit the Profile page and un-check the "Toggl Track can send newsletters by email" option.
Reports, alerts, and other (similar) emails
Emails in this category are contextual and directly related to your Toggl Track use. In other words, they will only be sent if certain parameters are met. Emails in this category include:
Weekly Overview Email. Can be disabled by un-checking the "weekly overview of tracked time" option on the Profile page.
Long-running timer notification. Disable it by un-checking the "Email about long running (over 8 hours) time entries" option on the Profile page.
Scheduled reports. Toggl Track allows you to schedule Saved reports to your email. To stop this email from being sent visit the Saved reports section, edit the relevant saved report and turn off the "Schedule to email" option.
Project alerts. To stop project-related updates from being sent via email visit the Alerts section in the webapp and delete the relevant alert.
Reminders to track time. Control (and delete) email-based tracking reminders by visiting the Reminders section in the webapp.
Core service emails
Emails in this category are necessary for Toggl Track to work and cannot be turned off. These include:
The welcome email
All subscription-related emails. In other words, billing & payment emails
Notifications about changes to the service