Email & Calendars overview

The postpress Email API gives your product a robust, secure connection to your users' mailboxes, with full access to historical and real-time email data. It supports bi-directional sync and full CRUD across every major email provider behind one REST interface, so a single integration covers Gmail, Microsoft 365, and any IMAP/SMTP mailbox.

What you can do with the Email API

• Retrieve email messages and threads, including content, sender and recipient details, and the rest of the message metadata.
• Organise inboxes by working with labels and folders the same way across providers.
• Update the status of an email, for example marking it as unread or starring it.
• Send email directly through the API.
• Search inboxes to locate specific emails or content.
• Handle and download attachments associated with emails.

With connected Google and Microsoft accounts you can also use the Calendar API to:

• Retrieve and manage calendars and events.
• Create events with attendees and an online meeting link.
• Receive webhook notifications for calendar events.

Google and Microsoft OAuth setup

postpress is compatible with every email provider, including IMAP-based mailboxes, with no preliminary configuration required. For Google and Microsoft, an important step of email integration in your application is to create your own OAuth application directly on Google and Microsoft so your users see your branded login screen. Once those applications are created, store the corresponding credentials in the postpress dashboard. When your development is finished, you need to start the verification process with Google, which can take weeks before moving to production.

For the full walkthrough, see the Google OAuth guide and the Microsoft OAuth guide, both written for the postpress API.

Email deliverability

In most cases, major email providers like Google, Microsoft, and IMAP providers automatically configure DKIM, SPF, and eventually DMARC when users set up their internal email systems. If you are simply building a system for email sync and manual sending from your app, you can bypass managing these settings. Just instruct users to connect their email; they will experience the same delivery results as with Outlook or Gmail.

However, if your system involves outreach or automatic sending at higher volumes, it is advisable to verify the proper configuration of these parameters to ensure optimal deliverability at scale.

If your company domain sends more than 5000 emails daily to Google or Yahoo, you need to maintain an abuse complaint rate of 0.3% or lower, or all company emails will be blocked by Google.

All traffic for your domain is included in this limit: newsletters, notifications, internal emails, and so on.