Email & webmail
Mailboxes, webmail, forwarders, spam filters and email delivery.
67 guides · page 2 of 4
Hourly email sending limits on cPanel hosting explained
Why cPanel hosting limits how many emails a domain can send per hour, what happens when you hit the limit, how to see queued mail and how to send newsletters properly.
How email hosting works: SMTP, IMAP, POP3, MX, SPF, DKIM and DMARC
Follow an email from sender to inbox: SMTP and MX records, IMAP vs POP3, and how SPF, DKIM and DMARC prove your mail is genuine so it lands in the inbox, not spam.
How to fix "SMTP authentication failed" email errors
Your email client says SMTP authentication failed or keeps asking for a password? Learn the correct cPanel mail settings and how to fix login, port and blocked IP problems.
How to fix email 550 errors (5.1.1, 5.7.1 and more)
A 550 bounce means the receiving server permanently refused your message. Learn what common 550 messages mean, from unknown users to SPF failures and blocklists, and how to fix them.
How to fix email 552 errors: message size exceeded or mailbox full
A 552 bounce means the message is too large or the recipient's storage is full. Learn how to tell which, send large files another way and fix your own mailbox quota.
How to fix email 554 errors (transaction failed and rejected)
A 554 bounce means the receiving server rejected your email outright, usually for spam, policy or blocklist reasons. Learn how to read 554 messages and fix your sending setup.
How to read email headers and trace a message's path
View full email headers in common mail apps and read Received lines, Authentication-Results, SPF, DKIM and DMARC verdicts, spam scores and delays to diagnose delivery problems.
How to use Roundcube webmail on cPanel hosting
Log in to webmail on port 2096, read, write and organise email in Roundcube, manage folders and attachments, and work safely from any browser.
IMAP vs POP3: which email protocol should you use?
How IMAP and POP3 work, how they differ in syncing, storage and multi-device use, their ports and encryption, and when POP3 still makes sense.
Import and export contacts in Roundcube webmail (vCard and CSV)
Move your address book into or out of Roundcube webmail with vCard or CSV files, create contact groups, and sync contacts with phones using CardDAV in cPanel.
Install and configure SpamAssassin on a Linux mail server
Install Apache SpamAssassin, connect it to Postfix with spamass-milter, tune the required score, whitelist senders, keep rules updated and train the Bayes filter.
Mail server software explained: Exim vs Postfix and Dovecot
How a mail server is built from an MTA (Exim or Postfix), an IMAP/POP3 server (Dovecot) and spam filtering, how they differ, and what you need to run your own mail server.
Manage the Exim mail queue in WHM (Mail Queue Manager, root)
Inspect, deliver and delete messages stuck in the Exim queue on your cPanel server with WHM Mail Queue Manager and command-line tools, and find the source of spam.
Manage the mail queue on Exim and Postfix from the command line
Command-line reference for viewing, inspecting, retrying and deleting queued messages on Exim and Postfix servers, finding the cause of deferrals and spotting spam floods.
Migrate email between servers with imapsync
Copy mailboxes from one IMAP server to another with imapsync: install it, run a dry run, migrate single or many accounts from a list, switch MX records and run a final sync.
Move email from another provider to cPanel (IMAP migration)
Migrate existing mailboxes to MdmHost cPanel email without losing messages: create accounts, copy mail over IMAP with an email app, switch MX records and reconnect devices.
MX record priority and backup MX servers explained
How MX priorities decide which mail server receives email, equal-priority load sharing, whether a backup MX is still a good idea, and common MX record mistakes.
Not receiving emails in cPanel: causes and fixes
Emails not arriving in your cPanel mailbox? Learn how to check MX records, email routing, mailbox quota, filters and spam settings, and trace missing messages step by step.
One SPF record for several mail services (and the 10-lookup limit)
Combine cPanel, Google Workspace, Microsoft 365, newsletter and CRM senders into a single valid SPF record, stay under the 10 DNS lookup limit and avoid common SPF errors.
Port 25 blocked on a VPS: why and how to send email anyway
Why many VPS and cloud providers block outbound port 25, how to test it, how to request unblocking, and how to send mail through an SMTP relay on port 587 with Postfix instead.
Other topics
- Getting startedYour first hour with a new server: access, logins and basics.83 guides
- cPanelFiles, databases, email, domains and every cPanel tool, step by step.67 guides
- WHM & resellingWHM, packages, reseller accounts, WHMReseller and running a hosting brand.53 guides
- WordPressInstall, secure, speed up, migrate and fix WordPress sites.49 guides
- Email & webmailMailboxes, webmail, forwarders, spam filters and email delivery.67 guides
- DomainsRegistering, transferring and managing domains and nameservers.27 guides
- SSL certificatesFree AutoSSL, Let's Encrypt, paid certificates and HTTPS.41 guides
- CloudLinuxCloudLinux setup and use: LVE limits, CloudLinux Manager, CageFS and PHP/Node.js selectors.31 guides
- LiteSpeedLiteSpeed Web Server, LSCache and the LiteSpeed Cache plugin: install, settings and tuning.35 guides
- Imunify360Malware scanning, firewall and proactive defence with Imunify360.24 guides
- SoftaculousInstall, update, clone and back up apps with Softaculous.24 guides
- WP SquaredcPanel's WordPress platform: sites, plugins, staging and backups.9 guides
- SitePadBuild and publish websites with the SitePad builder.9 guides
- SitejetDesign, edit and publish sites with the Sitejet builder.9 guides
- WHMResellerAlpha and master resellers with WHMReseller: install, setup and use.12 guides
- VirtFusionInstall, set up and manage VirtFusion: hypervisors, packages, servers and WHMCS integration.28 guides
- VirtualizorManage your VPS with Virtualizor: power, OS reinstall, VNC, IPs and backups.44 guides
- PleskWebsites, email, databases and settings in the Plesk panel.53 guides
- DirectAdminUsers, domains, email and reseller tools in DirectAdmin.41 guides
- WHMCSBilling, automation, products and client management with WHMCS.52 guides
- Control panelscPanel & WHM, Plesk, DirectAdmin and other panels on your VPS.107 guides
- SecurityKeys, passwords, firewalls and keeping a server patched.138 guides
- Networking & DNSIP addresses, reverse DNS, ports and traffic.72 guides
- Websites & appsWeb servers, WordPress, PHP, Node.js, SSL and app hosting.83 guides
- DatabasesMySQL, MariaDB, PostgreSQL, Redis and MongoDB on a VPS.80 guides
- Billing & accountInvoices, renewals, the client area and your account.9 guides
- TroubleshootingWhen something is not working: checks and fixes.127 guides
- Linux VPSSSH, packages, services and everyday Linux administration.265 guides
- Windows VPS & RDPRemote Desktop, Windows Server settings and Admin RDP tips.73 guides
- Docker & DevOpsContainers, Git deploys, automation, monitoring and backups.82 guides
Still stuck?
Ask MdmHost AI for a quick answer, or open a ticket and our team will take a look. We are here 24/7.