How to Set Up Email on Windows Plesk (Mail Server Configuration Guide)

Overview

Plesk on Windows uses its own built-in mail server — by default, MailEnable — to handle incoming and outgoing mail. If you’ve just spun up a Windows VPS or moved a domain to a Plesk-managed server, getting Plesk Windows email working is usually your first priority. The interface looks clean, but there are a handful of settings buried a few layers deep that trip people up.

This guide covers creating email accounts, configuring the mail server settings Plesk exposes, setting your DNS records correctly, and connecting a mail client like Outlook or Thunderbird. It also covers the problems you’re most likely to hit — authentication failures, mail landing in spam, and relay errors that the Plesk UI doesn’t explain well.

If your server is on a shared hosting plan, some of these server-level settings may be managed by the hosting provider. The steps here assume you have admin or reseller access in Plesk. If you’re on a Host & Tech VPS SSD Hosting plan, you’ll have full Plesk admin access and can follow every step below.

Prerequisites

• Plesk Obsidian 18.x or later running on Windows Server 2019 or 2022 (steps may differ slightly on older versions)
• Admin or domain owner access to the Plesk control panel
• A domain already added to Plesk with DNS either hosted through Plesk or pointed at your server’s IP
• Your server’s public IP address — you’ll need this when setting up DNS records
• Port 25, 465 (SMTPS), 587 (submission), 993 (IMAPS), and 995 (POP3S) open in your Windows firewall and any upstream firewall or security group
• Basic understanding of MX and SPF DNS records — if you need a refresher, read through the DNS section below before starting

Step-by-Step Instructions

Step 1: Verify the Mail Server Is Enabled in Plesk

Before creating any mailboxes, confirm the mail server service is actually running. This is the step most people skip.

1. Log into Plesk as an administrator.
2. Go to Tools & Settings > Mail Server Settings (under the Mail section).
3. Make sure MailEnable is listed and active. If you see a warning that the mail server is disabled, click Enable.
4. While you’re here, set the Maximum message size if you need to allow large attachments. The default is often 10 MB, which is low for business use. 30–50 MB is more practical.
5. Click OK to save.

📝 Note: Plesk on Windows uses MailEnable Community or Professional depending on your licence. The Community edition has some limitations around spam filtering and relay controls. If you’re on a commercial Plesk licence, MailEnable Professional is typically included.

Step 2: Configure Mail Server DNS Records

Your mail server won’t receive email reliably until your DNS is set correctly. You need at minimum an MX record and an SPF record.

1. In Plesk, go to Domains > yourdomain.com > DNS Settings.
2. Check that an MX record exists pointing to mail.yourdomain.com with a priority of 10. If it’s missing, click Add Record, select type MX, leave the domain field blank (for the root), set priority to 10, and enter mail.yourdomain.com as the value.
3. Confirm there’s an A record for mail.yourdomain.com pointing to your server’s public IP.
4. Add or verify an SPF TXT record on the root domain:
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   v=spf1 a mx ip4:YOUR.SERVER.IP.HERE ~all

   Replace YOUR.SERVER.IP.HERE with your actual server IP. This tells receiving mail servers that your server is authorised to send mail for your domain. Without this, outgoing mail will frequently land in spam or be outright rejected.

5. Click OK and allow up to 24 hours for DNS propagation, though it’s usually much faster.

⚠ Warning: Don’t set SPF to -all (hard fail) until you’ve confirmed all your legitimate sending sources are covered. Start with ~all (soft fail) to avoid accidentally blocking your own mail.

Step 3: Create an Email Account

1. Go to Domains > yourdomain.com > Mail.
2. Click Create Email Address.
3. Enter the local part of the address (e.g. info for info@yourdomain.com).
4. Set a strong password. Plesk will warn you if it’s too weak — don’t ignore this. Compromised mailboxes are one of the most common causes of spam relay abuse on shared servers.
5. Set a mailbox size if you want to cap it. Leaving it unlimited on a VPS with limited disk space will eventually cause problems.
6. Click OK.

Step 4: Configure Webmail Access (Optional)

Plesk includes Roundcube as a webmail client by default. To access it:

1. Go to Domains > yourdomain.com > Mail.
2. Click the Webmail link next to any mailbox, or navigate directly to https://webmail.yourdomain.com or https://yourdomain.com/webmail.
3. Log in with the full email address and password you set.

📝 Note: If webmail returns a 404, go to Tools & Settings > Webmail and confirm Roundcube is installed and set as the default.

Step 5: Connect a Mail Client (Outlook, Thunderbird, etc.)

Use these settings in your mail client. Always use the encrypted ports — avoid plain IMAP on port 143 or SMTP on port 25 for client connections.

• Incoming mail (IMAP): Server: mail.yourdomain.com, Port: 993, Security: SSL/TLS
• Incoming mail (POP3): Server: mail.yourdomain.com, Port: 995, Security: SSL/TLS
• Outgoing mail (SMTP): Server: mail.yourdomain.com, Port: 587, Security: STARTTLS (or port 465 with SSL/TLS)
• Username: Full email address (e.g. info@yourdomain.com)
• Password: The mailbox password you set in Step 3

In Outlook, go to File > Add Account, enter the email address, click Advanced Options, check Let me set up my account manually, then choose IMAP and enter the server details above.

⚠ Warning: If your Plesk server uses a self-signed SSL certificate, your mail client will show a certificate warning. I’d recommend installing a proper SSL certificate via Domains > yourdomain.com > SSL/TLS Certificates and using Let’s Encrypt. Self-signed certs aren’t suitable for production mail.

Step 6: Set Up DKIM Signing (Strongly Recommended)

DKIM adds a cryptographic signature to outgoing mail that proves it genuinely came from your server. Without it, your mail is significantly more likely to land in spam — especially with Gmail and Microsoft 365 recipients.

1. Go to Domains > yourdomain.com > Mail.
2. Click Mail Settings.
3. Check Use DKIM spam protection system to sign outgoing email messages.
4. Click OK. Plesk will automatically generate a DKIM key and add the required TXT record to your DNS zone if DNS is managed by Plesk.

If your DNS is managed externally (e.g. Cloudflare or a domain registrar), go to DNS Settings for the domain in Plesk, copy the DKIM TXT record that Plesk generated, and add it manually to your external DNS provider.

Common Issues & Troubleshooting

Mail client says “Authentication Failed” or won’t connect

This is usually one of three things: wrong username format, wrong port, or the mail server not listening on the port you’re trying to use.

Make sure the username is the full email address, not just the local part. Then check that the ports are actually open on the server:

netstat -ano | findstr ":993"
netstat -ano | findstr ":587"

If those ports show no listener, MailEnable may not be running. Open Services on the Windows server and confirm MailEnable IMAP Service and MailEnable SMTP Service are both running and set to Automatic start.

Outgoing mail is being rejected or marked as spam

The most common causes are a missing or broken SPF record, no DKIM signature, and no PTR (reverse DNS) record. Check your SPF and DKIM with MXToolbox (mxtoolbox.com/spf and mxtoolbox.com/dkim).

For PTR records, you need to contact Host & Tech support or your VPS provider to set a reverse DNS entry for your server’s IP — this is not something you can do in Plesk itself. The PTR should resolve to mail.yourdomain.com. Missing PTR records cause many mail servers, especially Microsoft’s, to reject or defer your mail.

Emails are sent but not received (MX record issue)

If you can send mail but incoming mail isn’t arriving, your MX record is almost certainly pointing to the wrong place or hasn’t propagated yet. Check the current MX resolution from an external perspective:

nslookup -type=MX yourdomain.com 8.8.8.8

This queries Google’s DNS directly, bypassing any local caching. If the MX record still shows your old mail server or registrar’s nameservers, you’ll need to update it and wait for propagation.

Webmail (Roundcube) login fails even with correct credentials

This error is annoyingly common after a server migration or domain transfer. Roundcube connects to the IMAP service locally, so if MailEnable IMAP is stopped or the mailbox wasn’t created properly in MailEnable’s own database (Plesk sometimes gets out of sync), the login will fail even though Plesk shows the account as active.

In Plesk, try deleting and recreating the mailbox. Before doing this, make sure to back up any existing mail via webmail or a connected client.

550 Relay not permitted error when sending

This means the mail server is refusing to relay mail on your behalf — usually because it doesn’t recognise the sender as an authenticated user. Confirm that SMTP authentication is enabled in your mail client settings. In Outlook, go to Account Settings > Outgoing Server and make sure My outgoing server (SMTP) requires authentication is checked, with Use same settings as my incoming mail server selected.

If you’re sending programmatically (PHP, a CMS, etc.), confirm the SMTP credentials in your application’s mail configuration are correct and that you’re connecting on port 587 with STARTTLS.

FAQ