Email Settings GuideQuick answer: Centrum email runs on Centrum. Every protocol connects to imap.centrum.cz. IMAP is on 993, POP3 on 995 and SMTP on 465, each secured with SSL. Your username is the full address and the mailbox password you set in Centrum settings lets you in. Your exact values also sit under The Send Upgrade in Centrum settings. Folders not syncing? Set the IMAP path prefix to INBOX.
What Changed Recently#
A host changes how you sign in more often than it changes the server names. Here is the current status for Centrum and what it means for your setup.
Worth knowing
Sending waits on a free upgrade. A new Centrum mailbox reads in a client but will not send until the free 15 GB upgrade is run in the webmail with a phone number.
Worth knowing
One outgoing host for the brands. A centrum.cz and an atlas.cz address read on different hosts, yet both send through the shared smtp.centrum.cz.
Worth knowing
Other domains follow centrum.cz. A Czech domain outside the main three, such as cbox.cz or mujmail.cz, uses the centrum.cz server settings.
Before You Begin#
Handle these two basics before anything else. Skip them and your email app will reject the connection even when every server value is correct.
1. Create the mailbox
Add the address under your mail settings in Centrum settings and set its password. That password is the one your apps use.
Where: Centrum then your mail settings
2. Open the send upgrade
Click reading and sending next to the address, then the send upgrade to read the server name and secure ports.
Where: The Send Upgrade
About Centrum and Atlas Mail#
Centrum is a long-running Czech and Slovak web portal and free mail service, run on the Economia Freemail platform. Addresses end in centrum.cz, centrum.sk or atlas.cz. They read in Outlook, Apple Mail or Thunderbird as well as in the Centrum webmail.
A centrum.cz address reads on imap.centrum.cz. An atlas.cz address reads on imap.atlas.cz. Both send through the shared host smtp.centrum.cz. The part that surprises people is that a new mailbox cannot send from a client until a free upgrade is run in the webmail.
| Domain | Incoming | Outgoing |
|---|---|---|
| centrum.cz | imap.centrum.cz 993 (POP pop3.centrum.cz 995) | smtp.centrum.cz 465 |
| atlas.cz | imap.atlas.cz 993 (POP pop3.atlas.cz 995) | smtp.centrum.cz 465 |
| Other domains | Use the centrum.cz servers | smtp.centrum.cz 465 |
Centrum Webmail Login#
You can always read your mail in a browser. The official sign in pages are:
Sending Needs a Free Mailbox Upgrade#
A fresh Centrum mailbox reads mail in a client right away, yet it will not send. Centrum keeps outgoing off until you run a free upgrade in the webmail. The upgrade uses a phone number and lifts the mailbox from 100 MB to 15 GB. Only then does smtp.centrum.cz accept your mail.
| Mailbox state | What a client can do |
|---|---|
| Basic, 100 MB | Reads mail, cannot send |
| Upgraded, 15 GB | Reads and sends |
Centrum IMAP Settings#
IMAP is the incoming choice Centrum points most people to. Mail stays put on the server, so a laptop and a phone read one shared inbox. Pull the exact server name from the send upgrade in Centrum settings.
| IMAP Server | imap.centrum.cz | |
| Port | 993 | |
| Encryption | SSL/TLS (required) | |
| Username | Your full email address, including @centrum.cz | |
| Password | Your mailbox password | |
| Authentication | Required |
Centrum POP3 Settings#
POP3 downloads mail to 1 device. Pick it only if you want a local copy on a single computer. Not sure? See the comparison below.
| POP3 Server | pop3.centrum.cz | |
| Port | 995 | |
| Encryption | SSL/TLS (required) | |
| Username | Your full email address | |
| Password | Your mailbox password |
Centrum SMTP Settings#
SMTP handles outgoing mail. If you can read mail but not send it, the problem is here.
| SMTP Server | smtp.centrum.cz | |
| Port (SSL) | 465 | |
| Port (STARTTLS) | 587 | |
| Encryption | SSL or STARTTLS (required) | |
| Username | Your full email address | |
| Password | Same as incoming mail | |
| Authentication | Required. Switch on outgoing server authentication in the client. |
465 with SSL. Many home connections block port 25. Centrum also supports 587 and 26 if 465 is blocked. Confirm outgoing authentication is on.
Check Centrum IMAP Settings Online#
You don't need to download anything to check Centrum IMAP settings online. This page is the lookup: every value is verified, current and copyable straight from your browser. Not sure your address uses Centrum servers? Type it below and find out instantly.
Does my email address use these settings?
Runs in your browser only. Your address is never sent anywhere or stored.
Want to verify the account itself before configuring an app? Sign in at Centrum webmail, which confirms your address and password work, then confirm an mailbox password exists. If both pass, any email app connects with the tables above.
Look Up IMAP Settings for Any Email Domain#
This page covers Centrum. For every other address, work email on a company domain included, we run a free online lookup database: imapsettings.com.
imapsettings.com
Complete email settings database, by Univik
Enter any email address and get the incoming and outgoing server settings for that domain in 1 step:
Your address is used only to find the settings for that domain. Nothing is stored or shared.
Username and Password#
Both come from the mailbox itself. The username is the whole email address and the password is the one you chose when you built the address in Centrum settings. A standard Centrum mailbox uses no mailbox password.
Username is the full address
Type you@centrum.cz in full, with the part after the at sign. Centrum turns down a bare mailbox name.
Put that same address on both incoming and outgoing.
Password is the mailbox one
This is the webmail password you set under your mail settings in Centrum settings, not your Centrum client area login. Reset it there if an app keeps refusing it.
The two factor prompt in the Centrum client area guards billing, not the mailbox connection.
Set Up Centrum in Email Clients#
The servers and ports are always the same. Only the menus differ. Jump to your app:
Outlook (Windows and Mac)
- In Outlook select Add Account, then turn on manual setup under Advanced options.
- Choose IMAP and set incoming to
imap.centrum.czon 993 with SSL. - Set outgoing to the same server on 465 with SSL.
- Enter the full address and mailbox password when Outlook prompts you.
- Send a test message to yourself to prove both paths.
Apple Mail (macOS)
- In Mail select Add Account, then pick Other Mail Account.
- Give your name, Centrum address and password, then continue.
- Enter imap.centrum.cz with SSL on incoming and outgoing.
- Keep the SSL ports so nothing sends in plain text.
- Save and wait for the mailbox to load.
iPhone and iPad
- In Settings open Mail, then tap Mail Accounts and Add Account.
- Tap Other then Add Mail Account and fill your details.
- Keep IMAP chosen and put imap.centrum.cz in both server boxes.
- Leave the secure ports iOS fills, since Centrum expects SSL.
- Tap Save and let iOS run its check.
Android
- Open your mail app and tap Add account, then Other or IMAP.
- Put in your address and password. Switch to manual setup if it stalls.
- For incoming use imap.centrum.cz on 993 over SSL.
- For outgoing use smtp.centrum.cz on 465 over SSL.
- Save and swipe down to fetch your mail.
Thunderbird
- In Thunderbird pick Account Actions, then Add Mail Account.
- Type your name, Centrum address and password, then Continue.
- Wait for detection, then make sure IMAP with SSL is picked.
- If detection fails, type imap.centrum.cz in yourself.
- Hit Done and the folders fill in on the first sync.
Centrum Webmail Settings#
Server settings connect your apps. The controls here shape how the mailbox acts on its own. They live in the Centrum webmail, opened in any browser.
Signature
Add one in the webmail preferences. It rides on mail sent from webmail. A desktop app keeps a signature of its own.
Vacation Auto Reply
Set an autoresponder in Centrum settings and give it start and end dates. The Centrum server delivers it, so it fires even when your machine is off.
Filters and Folders
Create filters from the Centrum webmail filters in Centrum settings. A server side rule sorts a message ahead of any device fetching it. A rule set inside an app only works while that app is running.
Spam and Blocked Senders
Centrum runs SpamAssassin on incoming mail. Set the threshold and block unwanted senders in Centrum settings. Flagged mail lands in the junk folder for a look.
POP3 vs IMAP#
| Feature | IMAP | POP3 |
|---|---|---|
| Where mail lives | On the Centrum server | Downloaded to 1 device |
| Multiple devices | ✅ Everything stays in sync | ❌ Each device sees different mail |
| Sent and deleted mail | ✅ Synced everywhere | ⚠️ Stays only on that device |
| Offline reading | ⚠️ Cached mail only | ✅ Full local copy |
| Server storage used | Yes, counts against your quota | Can be freed after download |
| Best for | Phone + computer, everyday use | Single PC, local archives |
Centrum Mail at a Glance#
Every value in one place. Match the incoming host to your domain. Run the free upgrade so sending works:
| centrum.cz IMAP | imap.centrum.cz, 993, SSL |
| atlas.cz IMAP | imap.atlas.cz, 993, SSL |
| POP3 | pop3.centrum.cz or pop3.atlas.cz, 995, SSL |
| SMTP (shared) | smtp.centrum.cz, 465 SSL or 587 StartTLS |
| Authentication | Required, same login as incoming |
| Sending | Needs the free mailbox upgrade |
| Webmail | email.centrum.cz |
Troubleshooting Centrum Connections#
Find the exact error your email app shows, then apply the fix:
| Error you see | What it means | Fix |
|---|---|---|
| Username or password rejected | Short username or wrong password | Use the full email address with the mailbox password from Centrum, not the client area login. |
| Cannot send on port 25 | ISP blocks the default SMTP port | Switch outgoing to 465 with SSL. Centrum also accepts 587 and 26 if 465 is blocked. |
| Reads mail but will not send | Mailbox not upgraded yet | A new Centrum mailbox keeps sending off. Open the Centrum webmail settings and run the free upgrade with a phone number, which lifts it to 15 GB and lets smtp.centrum.cz send. |
| atlas.cz box will not receive | Wrong incoming host | An atlas.cz address does not read on imap.centrum.cz. Set incoming to imap.atlas.cz on 993 with SSL, then send through the shared smtp.centrum.cz. |
| Cannot connect to server | Wrong port or encryption | Set 993 with SSL incoming and 465 with SSL outgoing. A firewall on your own machine can block it as well. |
| Repeated password prompt | Short username or a typo | Clear the saved login, then put in the full address with the mailbox password. |
| Messages stuck in Outbox | SMTP authentication is off | Enable "outgoing server requires authentication" with the same login as incoming mail. |
| Inbox loads but folders missing | IMAP path prefix left blank | Centrum keeps folders under INBOX. Open the account's advanced IMAP settings and type INBOX in the path prefix field, then let the client resync so Sent and Drafts appear. |
| Sent mail does not show on my phone | Folder sync not set up | Over IMAP the Sent folder lives on the server, so it shows once folders sync. If it stays hidden, set the IMAP path prefix to INBOX so the folder list loads. |
Reader Reported Fixes
Copy from the send upgrade. When a manual setup will not connect, the the send upgrade page in Centrum settings prints the exact server name and ports for that mailbox. Pasting those in clears the guesswork behind most failed setups.
Test the login in webmail first. Sign in at webimap.centrum.cz with the full address and mailbox password. If webmail works, the credentials are right and the issue sits in the app settings.
When Centrum Folders Do Not Sync#
Sometimes a Centrum account signs in over IMAP yet the folders never appear. The inbox loads, but Sent, Drafts and any folders you made stay missing. New mail is slow to show too. Centrum names the fix on its own help pages: a client field called the IMAP path prefix has been left blank, so type INBOX into it.
The path prefix (some clients call it the IMAP server directory or namespace) tells the client where your folders live on the server. Centrum keeps them under INBOX, so a client that looks at the top level finds nothing to sync. Setting the prefix to INBOX points the client at the right place. The folders then line up. It is worth trying whenever a Centrum or Atlas account connects but the folder list is empty.
| Client | Where the field is |
|---|---|
| Thunderbird | Server Settings, Advanced, IMAP server directory |
| Apple Mail and iOS | Account, Advanced, IMAP Path Prefix |
| Android setup | The path prefix field on the incoming server step |
Moving Mail In or Out?#
Centrum mail speaks plain IMAP, so a mailbox moves in or out like any Centrum account. Each folder stays on the server until the move finishes.
Take a copy first. Back up the mailbox before a move. A note that arrives mid switch can sit on either side. A copy keeps you safe.
Carrying mail across? The Univik Email Migration Tool moves each folder over an IMAP link. Give it the Centrum server name and mailbox password on this side and the other account opposite.
Rather hand it off? Our Email Migration Services team runs the whole move and verifies each folder arrived.
Use These Settings in Univik Email Backup#
The same IMAP settings above let you download your complete Centrum mailbox to your computer. Univik Email Backup saves everything as PST, MBOX, EML or PDF files you keep forever, even if the account closes.
- Download Univik Email Backup and install it on Windows.
- Select Centrum from the source list. If it isn't listed by name, choose IMAP.
- Give the complete email address with your mailbox password. The login name is always the whole email address.
- When the backup tool wants server details, hand it imap.centrum.cz on port 993 with SSL for Centrum. Take those values straight from the IMAP table above, with port
993over SSL. - Pick a saving format and folder, then start the backup. Large mailboxes download in the background.
Univik Tools That Use These Settings#
Many people land here while migrating or archiving a mailbox. All 3 tools use the same IMAP settings from this page:
Email Backup
Download your complete Centrum mailbox to PST, MBOX, EML or PDF before switching or closing the account.
Email Backup Tool →
Email Migration Tool
Copy every folder from Centrum straight into Gmail, Microsoft 365 or any other account. No manual export needed.
Email Migration Tool →
Email Converter Tool
Already have MBOX, EML or OST files from an old export? Convert them to PST, PDF or any format your new app opens.
Email Converter Tool →Prefer to hand the whole migration to experts?
If the hostnames and passwords feel like busywork, you can let the tool handle it. Univik's migration team handles the complete project: planning, transfer, verification and a report showing every folder made it. Since 2013, for single mailboxes up to full company moves.
Email Settings Glossary#
IMAP
Internet Message Access Protocol. Reads mail that stays on the server. Use imap.centrum.cz on 993 with SSL for a centrum.cz address. An atlas.cz address uses imap.atlas.cz.
POP3
Post Office Protocol version 3. Downloads mail to one device. Use pop3.centrum.cz on 995 with SSL. An atlas.cz address uses pop3.atlas.cz.
SMTP
Simple Mail Transfer Protocol. Sends your outgoing mail through smtp.centrum.cz on 465 with SSL. Both centrum.cz and atlas.cz send through this one host.
SSL and TLS
The encryption Centrum needs. Use SSL on 993 and 995 for reading. Use SSL on 465 (or StartTLS on 587) for sending.
Mailbox Upgrade
A free upgrade that switches sending on. Done in Centrum webmail with a phone number, it lifts the mailbox from 100 MB to 15 GB and lets a client send.
Server Requires Authentication
The setting that tells the outgoing server to sign you in. Tick it and use the same address and password as for incoming mail.
Full Email Address
Your username is the whole address, like you@centrum.cz or you@atlas.cz. Type it in full on the incoming and the outgoing server.
Centrum Webmail
The browser view of your mail. It is also the place to run the free mailbox upgrade that switches sending on.
The Atlas Servers
An atlas.cz address reads on imap.atlas.cz and pop3.atlas.cz, then sends through the shared smtp.centrum.cz, the same outgoing host as centrum.cz.
Economia Freemail
The platform behind Centrum, Atlas and other Czech domains such as cbox.cz and mujmail.cz. A domain outside the main three uses the centrum.cz settings.
Port 465
The SSL port for sending on smtp.centrum.cz. Port 587 with StartTLS is the alternative. Both need authentication on.
Centrum
A long-running Czech and Slovak web portal and mail service. Addresses end in centrum.cz, centrum.sk or atlas.cz and read at the Centrum webmail.
IMAP Path Prefix
A client field, also called the IMAP server directory or namespace, that says where folders live on the server. On Centrum, set it to INBOX if folders do not sync.
Server Folders
Sent, Drafts, Spam and the folders you make, which live on the Centrum server over IMAP. They appear once the path prefix points the client at INBOX.
Resync
Refreshing the folder list from the server after a settings change. Save the INBOX path prefix, then let the client resync so the missing folders show.
How We Verify These Settings#
Univik builds email backup, migration and converter software since 2013. Our tools sign in to Centrum over IMAP and SMTP every day for thousands of users, so a changed server, port or login rule shows up in our connection logs before most guides notice it.
Every value on this page is confirmed with three checks: a live IMAP and SMTP connection from Univik Email Backup, a comparison against the Centrum guides and a sign in with a real mailbox using the full address. We re verify after any provider announcement and at least once a quarter.
Found something that no longer matches what Centrum shows you? Tell us and we will retest and update the page, with the change logged in what changed recently.
Help & Support
Frequently Asked Questions
For a centrum.cz address, incoming is imap.centrum.cz on 993 with SSL and outgoing is smtp.centrum.cz on 465. For an atlas.cz address, incoming is imap.atlas.cz. The username is your full address.
A new Centrum mailbox keeps sending switched off until you run a free upgrade. Open the Centrum webmail settings and upgrade the mailbox with a phone number, which lifts it from 100 MB to 15 GB and lets smtp.centrum.cz send.
Sign in at the Centrum webmail, open the mailbox settings and choose the free upgrade. It asks for a phone number, then raises the mailbox to 15 GB. After that a client can send through smtp.centrum.cz.
An atlas.cz address reads on imap.atlas.cz on 993 with SSL. POP3 is pop3.atlas.cz on 995. Sending goes through the shared smtp.centrum.cz on 465, the same outgoing host as centrum.cz.
Send through smtp.centrum.cz on 465 with SSL. Port 587 with StartTLS also works. Turn authentication on and use the same address and password as for incoming. Sending also needs the free mailbox upgrade.
A Centrum domain outside the main three uses the centrum.cz settings. Enter imap.centrum.cz for incoming and smtp.centrum.cz for outgoing, with your full address as the username.
IMAP is the better default. It keeps mail on the Centrum server so a phone and a laptop show the same inbox. POP downloads to one device, which suits a single machine you back up yourself.
Your mailbox password, the one for the Centrum mailbox. If a client keeps refusing it, sign in to the webmail at email.centrum.cz first. If the webmail also refuses it, reset the password there.
Open email.centrum.cz and sign in with your full address and mailbox password. The webmail is also where you run the free upgrade that switches sending on.
A Centrum account can connect over IMAP yet show no folders because the IMAP path prefix is blank. Centrum keeps folders under INBOX, so type INBOX in the client's IMAP path prefix field, sometimes called the IMAP server directory, then resync. Sent, Drafts and your own folders then appear on every device.
Other Email Provider Settings
Summary: Centrum Settings at a Glance
- IMAP: imap.centrum.cz, port 993, SSL/TLS
- POP3: imap.centrum.cz, port 995, SSL/TLS
- SMTP: smtp.centrum.cz, port 465 or 587
- Username is always your full email address
- Centrum mailbox on the Centrum servers
- Pick IMAP for phone + computer sync
- Full address as the username
- Username is always the full email address