How to Backup Microsoft 365 Outlook Email to a PST File

by | Nov 9, 2025

Introduction

Backing up your email is one of the most important steps you can take to protect your data. If you use Microsoft Outlook for desktop app, you can backup Outlook email to create a PST file to save your emails, contacts, and calendar entries. This guide explains how even non-technical users can do this easily, why PST files are useful, and what limitations exist.

Click open the headers below to learn more about  Microsoft 365 work accounts. Support options are available for professional assistance.

What is a PST File and Why Use It?

A PST file (Personal Storage Table) is a data file used by Outlook to store your email messages, contacts, and calendar items. Here’s why it matters:

  • Backup: If something goes wrong with your mailbox, you can restore your data from the PST file.
  • Migration: Moving to a new computer? A PST file lets you transfer your Outlook data easily.
  • Archiving: Free up space in your mailbox by storing older emails in a PST file.

Important: You can only backup Outlook email this way using Outlook for desktop. The feature is not available in Outlook Web Access (OWA). This is because OWA is server-based (not PC-based), so Microsoft does not provide a PST export option OWA.

In Exchange Online, network administrators backup Outlook email mailbox using Exchange Admin Center (EAC) or PowerShell export tools, which require admin-level permissions and technical expertise. You can read about these procedures here. If you are not familiar with Powershell or admin-level procedures in Exchange Online please contact us for help. 

What Can You Backup with a PST File?

When you create a PST file, you can include:

  • Emails from all folders or just one mailbox.
  • Contacts so you don’t lose important details.
  • Calendar entries for meetings and reminders.

You can even export specific folders or individual mailboxes if you don’t need everything.

Step-by-Step: How to Create a PST File in Outlook

Follow these steps to backup Outlook email, and/or contacts, and/or calendars:

  1. Open Outlook (Desktop Version).
  2. Click File > Open & Export > Import/Export.
  3. Choose Export to a file and click Next.
  4. Select Outlook Data File (.pst) and click Next.
  5. Select the folders you want to back up (e.g., Inbox, Contacts, Calendar).
  6. Choose a location to save the PST file and click Finish.
  7. (Optional) Add a password for extra security. If you add a password, record the password in a place that you can be sure to refer to in future. If you lose this password, you will not be able to access the backup.

Your PST file is now ready. You can store it on an external drive or cloud storage for safekeeping.

Limitations and Advanced Options
  1. You can only backup Outlook email using Outlook for desktop. The feature is not available in Outlook Web Access (OWA), for reasons explained above.
  2. You can backup Outlook email using Exchange Admin Center (EAC): PST export/import is possible here, but it requires advanced skills. See these guidance notes. In addition to importing/exporting individual accounts, network administrators can manage procedures at scale. For instance, EAC is appropriate for importing multiple user accounts simultaneously. If you need this kind of support, contact us for expert help.

How to Use Microsoft 365 MailTips to Improve Email Performance

by | Oct 6, 2025

Introduction: What Are MailTips in Microsoft 365?

Microsoft 365 MailTips are real-time alerts that appear while you compose emails in Outlook or Outlook on the web. These tips help users avoid common mistakes like emailing external recipients, contacting someone who’s out of office, or sending messages that are too large. MailTips are built into Exchange Online and are designed to improve communication and reduce email-related errors. Lastly, mailtips are managed at server level by an adminustrator in Exchange Admin Center (EAC).

Click open the headers below to learn how mailtips can help your users get more from their work with email. Be sure to contact us for advice if you are in doubt, or if you need to deal with bulk application of mailtips using Powershell.

How Microsoft 365 MailTips Work

When a user begins composing an email, Outlook queries the Exchange server to check for conditions that trigger MailTips. If any conditions are met, a notification appears instantly. These alerts are designed to be helpful and informative. For instance, a mailtip might be established to warn a user if a file attachment would cause the email to exceed email size limits. 

Common MailTips Include:

  • Message size limit warnings
  • Notice that a colleague has configured Automatic Out-of-Office replies
  • Warning of Large distribution list in send:, cc:, and bcc: fields
  • Restricted recipients

Configuring Microsoft 365 mailtips like these help users make smarter decisions before sending emails.

MailTips Limitations and Alternatives

MailTips do not scan email content for sensitive data like credit card numbers. For that, use:

  • Data Loss Prevention (DLP): Detects and blocks sensitive content.
  • Sensitivity Labels: Automatically classify and protect emails.

For example, in situation where it is inappropriate to include a full length credit card number in an email, conditions can be configured to automatically obscure all but a few numbers of the card as the server processes the outgoing email, ask the sender to edit the email, or block the email. In this way, Exchange Online can activeley monitor email traffic to help a business control personal data that might lead to loss ofr damage to customers. These utilities are especially useful in financial services and medicine.

DLP and Sensitivity labels are subject to adequate Microsoft 365 licensing – please ask if you need more information.

Example: Setting Up a MailTip for Large Attachments

Microsoft 365 allows admins to configure MailTips that warn users when their email might exceed the organization’s size limits. While the maximum message size can be set up to 150 MB, the default is often 25 MB or 35 MB, depending on your configuration. In theory, Microsoft 365 can handle large attachments. However, this causes problems for server storage at scale, and large emails are often dropped by external servers as they pass to recipients. For large files, use file sharing with links to files stored in OneDrive and Sharepoint.

Use this workflow to establish a custom Mailtip to warn users about large attachments:

Step-by-Step Guide Using Exchange Admin Center (EAC)

  1. Log in to the Exchange Admin Center\ Navigate to https://admin.exchange.microsoft.com and sign in with your admin credentials.
  2. Go to Recipients > Mailboxes\ Select the mailbox you want to configure.
  3. Open Mailbox Properties\ Click the mailbox name to open its details pane.
  4. Navigate to Others > Manage MailTip\ In the flyout panel, find the Manage mail tip option.
  5. Enter Your Custom MailTip\ Example:\ “Warning: This mailbox has a 25 MB attachment limit. Large files may cause delivery failure.”
  6. Save Changes\ Click Save to apply the MailTip.

!!! Note: MailTips are limited to 175 characters and support basic HTML formatting.

Optional: Use PowerShell for Bulk Configuration

If you need to handle several email accounts, it is easier to do this using Powershell to perform a batch operation. Powershell can be used to manage this indivdually, too. Powershell is beyond the scope of this article, and if you need help with Powershell, please contact us.

Summary

Microsoft 365 MailTips helps prevent email errors and improves communication. By configuring Microsoft 365 MailTips—especially for common issues like large attachments—admins can reduce support tickets, avoid non-delivery reports, and maintain a professional email environment.

About ComStat.uk: Internet Service Provider Comstat provides IT support, web hosting, and media services including website design, Microsoft 365 setup, and audio/video production, serving businesses across Denbighshire, North Wales and Wirral from Ruthin, and Lancashire and the Northwest from Bolton.

What Is a Shared Mailbox in Microsoft 365 and Why Your Business Should Use One

by | Oct 4, 2025

What Is a Shared Mailbox in Microsoft 365?

A Microsoft 365 shared mailbox allows multiple users to read and send emails from a common email address, such as support@yourcompany.com or accounts@yourcompany.com. These mailboxes are ideal for teams that need to manage group communications efficiently.

Shared mailboxes do not require a separate Microsoft 365 license, but any user accessing them must have a paid Microsoft 365 license. This makes them a cost-effective solution for collaborative email management.

Click open the headers below to learn more about shared mailboxes. Please read through this entire article before engage Microsoft for restoration of service. Be sure to contact us for general advice if you are in doubt. Support options are available for professional assistance.

Why are Shared Mailboxes Useful?

Shared mailboxes offer several practical advantages for businesses:

  • Team Collaboration: Multiple users can access the same mailbox, making it perfect for departments like support, sales, or accounts.
  • Offboarding Employees: When an employee leaves, their mailbox can be converted into a shared mailbox to retain access to important communications.
  • Shared Calendars: Teams can use the shared mailbox calendar to coordinate meetings, deadlines, or events.
  • File and Folder Sharing: Shared mailboxes can also serve as a central location for storing and accessing shared documents.

Here are some common scenarios where shared mailboxes are great business solutions:

  • Customer Support Teams: Centralize incoming queries and allow multiple agents to respond.
  • Accounts Departments: Manage invoices and financial communications from a single address.
  • Project Teams: Share calendars and documents related to specific projects.
  • HR Departments: Handle job applications and internal communications securely.
Creating a Shared Mailbox Without a License

To create a shared mailbox, you don’t need to assign a Microsoft 365 license to the mailbox itself. This is how to do it:

  1. Create a New User in Microsoft 365 Admin Center
    1. Go to Users > Active Users and click Add a user
    2. Fill in detail field (e.g., name, email address)
      1. Do not assign a license
  2. Convert the User to a Shared Mailbox
    1. After creating the user, go to Mailboxes in Exchange Admin Center
    2. Select the user and choose Convert to shared mailbox
  3. Assign Permissions
    1. Add users who need access by assigning Full Access and Send As permissions.

Using a shared mailbox in this way ideal for setting up departmental mailboxes like info@, sales@, or hr@

Converting an Existing User to a Shared Mailbox After Offboarding

When an employee leaves, their mailbox may contain valuable information. Instead of deleting the account, you can convert it to a shared mailbox:

  1. Convert to a Shared Mailbox
    1. Navigate to Exchange Admin Center, select the user’s mailbox, and click Convert to shared mailbox.
  2. Remove the License
    1. In the Microsoft 365 Admin Center, remove the user’s license to avoid ongoing costs.
  3. Assign Access to Relevant Team Members
    1. Add team members who need access to the mailbox for continuity.
      This approach preserves email history and ensures business continuity without incurring additional licensing fees.

Using a shared mailbox this way preserves email history and ensures business continuity when an employee leaves without incurring additional licensing fees.

Stroage Limits, Archiving, and Compliance

Storage Limits

  • A shared mailbox without a license has a 50 GB storage limit
  • If the mailbox exceeds 50 GB, you must assign an Exchange Online Plan 2 license (or equivalent) to increase the limit to 100 GB and enable archiving features

Archiving and Compliance

  • In-Place Hold or Litigation Hold: If you need to place the mailbox on hold for compliance or legal reasons, a license is required.
  • Archiving: A shared mailbox can have an archive mailbox, but this feature also requires a license. Without it, archiving isn’t available.
  • Retention Policies: These can still apply to a shared mailbox, but advanced compliance features often need licensing.

Best Practice

  • For most departmental or offboarding scenarios, the 50 GB limit is sufficient.
  • If you anticipate heavy email traffic or need compliance features, keep a license assigned even after conversion.
Summary

Shared mailboxes in Microsoft 365 are a powerful tool for improving team collaboration, managing transitions, and streamlining communication. They are easy to set up and configure, cost-effective, and versatile—making them a smart choice for businesses of all sizes.

About ComStat.uk: Internet Service Provider Comstat provides IT support, web hosting, and media services including website design, Microsoft 365 setup, and audio/video production, serving businesses across Denbighshire, North Wales and Wirral from Ruthin, and Lancashire and the Northwest from Bolton.