Do these 3 things before closing this tab:
1Fix the driver behind crashes, sound loss and screen glitches2Repair Windows errors before they cause bigger problems3Scan for outdated or missing drivers - takes under a minuteTo run email from a VPS, install and configure Postfix as the SMTP transfer agent, add Dovecot only when you need mailbox access or SMTP authentication, secure authenticated submission with TLS, publish matching DNS records, and verify that the server cannot relay messages for strangers. Postfix moves messages between servers; Dovecot can provide IMAP/POP mailbox access and a SASL authentication socket that Postfix uses for authenticated clients. Installing the packages alone does not create reliable delivery: hostname, reverse DNS, sender authorization, relay policy, patching and abuse monitoring all affect whether messages arrive.
Need a server to try this on? Antihost offers Linux VPS plans with NVMe storage, full root access and a 14-day free trial.
Decide what your VPS must do
There are two distinct jobs in a conventional mail setup. Postfix is the mail transfer agent (MTA): it accepts SMTP connections, queues messages, and delivers them to other mail servers. Dovecot is a mailbox service: it lets users read mail over IMAP or POP3 and can authenticate SMTP submission through SASL. You can run Postfix for system notifications without offering mailboxes, but client submission with usernames and passwords normally needs a SASL provider such as Dovecot.
As an Amazon Associate I earn from qualifying purchases.
Choose the mail flow before editing files:
- Direct delivery: your VPS connects to recipient mail servers on port 25. You control the queue and data, but you also own sender reputation, DNS identity, abuse response and delivery troubleshooting.
- Outbound relay: Postfix hands mail to a separate SMTP relay. This can simplify port-25 restrictions and reputation management, but introduces a provider dependency, recurring cost and another system whose authentication and sender rules must be configured.
- Inbound mailbox server: Postfix receives mail for your domain and Dovecot exposes those messages to users. This adds storage, IMAP/POP security, backups and account administration.
This guide describes a direct Postfix installation on Ubuntu, with optional Dovecot SASL and mailbox access. Provider policies differ, so check your VPS host before committing to direct delivery.
Prerequisites and decisions
Prepare these items first:
- A static public IPv4 address, and an IPv6 address only if you will configure and monitor IPv6 delivery.
- A fully qualified hostname such as
mail.example.comthat you control in DNS. - Administrative access to an Ubuntu VPS and its DNS zone.
- A provider policy that permits mail traffic, including outbound port 25, and a process for setting reverse DNS (PTR).
- A decision about the accepted domain, trusted network range, mailbox format and local usernames. Ubuntu’s Postfix guidance asks you to settle these values before configuration.
- A certificate whose name covers the SMTP hostname, with its private key stored so only the mail service can read it.
Keep the server hostname, forward DNS, reverse DNS and certificate name aligned. For example, if the server identifies itself as mail.example.com, its A record should resolve to the VPS address, the address’s PTR should normally point back to that hostname, and the SMTP certificate should include that name. A mismatch does not always stop SMTP, but it is a common reason for warnings and poor trust.
#1 Best Overall
- [Ultra-Lightweight Ear Buds Designed for Small Ears] Each earbud weighs only 3.7g and features a compact, ergonomic in-ear design made especially for small ears. Secure, low-profile, and comfortable for workouts, all-day wear or overnight sleeping.The ultra-slim profile sits flush in your ear with no hard edges poking or rubbing, so you can even sleep on your side without discomfort.
- [Immersive Stereo Sound with TOZO OrigX Technology] TOZO OrigX tuning delivers clear vocals, balanced mids, and natural stereo sound for music, podcasts, and videos.
- [Long Battery Life for Daily Use] Get up to 7 hours of playtime on a single charge, with up to 32 hours total using the charging case—ideal for workdays, commuting, and extended listening sessions.
- [Bluetooth 5.3 & Stable Connection] Bluetooth 5.3 provides fast pairing, stable wireless performance, and reduced dropouts as you move around home or office.
- [Deep Bass with Clear Vocals] High-performance drivers produce punchy bass while keeping vocals clean and detailed for everyday listening.
Install Postfix on Ubuntu
- Update package metadata and install Postfix:
sudo apt updatesudo apt install postfix - When the package configuration screen appears, select Internet Site if this VPS will deliver mail directly.
- Enter the system mail name when prompted. Use the domain that should appear on local mail, then review the generated configuration rather than assuming the wizard chose every value correctly.
- Check the service:
sudo systemctl enable --now postfixsudo systemctl status postfix
Ubuntu identifies Postfix as its default supported mail transfer agent. The package creates /etc/postfix/main.cf for global settings and /etc/postfix/master.cf for service definitions. Make a backup before changing either file:
sudo cp /etc/postfix/main.cf /etc/postfix/main.cf.backup
sudo cp /etc/postfix/master.cf /etc/postfix/master.cf.backupSet the core Postfix identity and relay policy
Use postconf to inspect effective values and edit /etc/postfix/main.cf with your preferred editor. The following settings illustrate the roles that must be correct; replace the example domain, hostname and network with your values.
myhostname = mail.example.com
mydomain = example.com
myorigin = $mydomain
inet_interfaces = all
mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain
mynetworks = 127.0.0.0/8 [::1]/128
home_mailbox = Maildir/
relay_domains =
smtpd_recipient_restrictions =
permit_mynetworks,
permit_sasl_authenticated,
reject_unauth_destinationWhat each setting controls
myhostnameis the server’s canonical SMTP name and should match DNS and the certificate.mydestinationlists domains for which this host is the final destination. Add only domains you actually host.mynetworksdefines networks trusted to relay without a password. Keep it narrow. The loopback ranges are a safe starting point; never add an entire public or hosting-provider range merely to make a client work.home_mailbox = Maildir/stores each local user’s mail in a Maildir under that user’s home directory. If you choose another mailbox format, configure Dovecot to read the same format.reject_unauth_destinationprevents the server from relaying to arbitrary outside domains. It is the essential safeguard against an open relay.
After editing, validate syntax and reload:
sudo postfix check
sudo systemctl reload postfix
postconf -nIf postfix check reports an error, fix it before accepting Internet mail. The postconf -n output is also the quickest way to spot an unexpected relay rule or a value overridden elsewhere.
Add Dovecot for SMTP authentication and mailboxes
Install the Dovecot core package for SASL. Add the IMAP package only if users need to read mail from an IMAP client:
sudo apt install dovecot-core dovecot-imapdDovecot’s exact configuration is split across files under /etc/dovecot and can vary by Ubuntu release. The important design is that Postfix connects to a private Unix socket owned by Dovecot. In Dovecot’s authentication service, create a Postfix listener similar to:
Rank #2
- 【IP68 Waterproof Multifunctinal Smart Watch】Torjalph fitness activity tracker smart watch is IP68 waterproof technology ,you can wear it when swimming,handwashing,it's rain-proof which means that you perform multiple exercise modes outside without worrying about sweat or rain corroding your fitness smart watch,and this watch equipped with a 230 mAh large capacity battery magnetic charging ,and this sports activity tracker watch can be used 5-7 days If fully charged.
- 【Larger 1.83'' Full Screen Watch & Multi-dial Selection】1.83 inch full HD color touch screen smart watch for men / women provides excellent 240*284 resolution image quality ,This Bluetooth smart watch offers a better touch experience and remarkable immersion and ,more than 200 watch faces for you to choose from App"Da Fit ", you can change the dial style according to your mood to wear keeping the world on your wrist
- 【Accurate Activity Tracker Smart Watch 】sports watch activity tracker uses sweat and dust resistant breathable silicone strap, our Fitness Tracker Smart Watch for Android iOS Phones supports 12 sports modes,walking,running,bicycle,swimming,badminton,basketball,football,rope skipping. This bluetooth calls smart watch for men women is lightweight and stylish, bringing more convenient and relaxing sports experience while also providing more protection.
- 【Your 24 Hour Personal Daily Health Monitor】Fitness watch for women men full touch screen IP67 waterproof bluetooth smartwatch for Android iOS Phones with heart rate blood pressure monitor multifunction Andriod smart watch with steps counter sleep monitor sports fitness watch, monitoring blood oxygen saturation allows you to understand your physical condition in real time to track fitness progress ,to know your health status in time.
- 【More Functions Bluetooth Call Smart Watch】This fitness activity smart watch full screen for iPhone and Android phones includes a bunch of new features including:The bluetooth smart watch can hang up the phone, receive and display WhatsAPP /Text /Facebook /Twitter /Messenger reminder.Support sedentary reminder, alarm clock, stopwatch, timer,weather information,music control, remote camera control compatible with Android 5.0 and above or iOS 9.0 and above smartphones.
service auth {
unix_listener /var/spool/postfix/private/auth {
mode = 0660
user = postfix
group = postfix
}
}Ensure Dovecot enables an authentication mechanism suitable for a TLS-protected connection, for example:
Free tools Windows power users keep installed
One-click scans. No signup required.
auth_mechanisms = plain loginDo not treat plain or login as safe on an unencrypted connection: they transmit credentials in an encoding that is reversible. Require TLS on the submission service before advertising or accepting these mechanisms. Configure Dovecot’s mail location to match the Postfix mailbox format, create user accounts, and set Dovecot’s certificate and key paths if it will also provide IMAP.
Point Postfix at the socket and enable SASL in main.cf:
smtpd_sasl_auth_enable = yes
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous
smtpd_sasl_local_domain = $myhostname
broken_sasl_auth_clients = yesRestart both services and check for configuration errors:
sudo systemctl restart dovecot
sudo systemctl restart postfix
sudo systemctl status dovecot postfixAuthentication gives a client permission to submit mail; it must not grant unrestricted relay to unauthenticated connections. Keep permit_sasl_authenticated before reject_unauth_destination, and leave unauthenticated Internet clients subject to the destination check.
Rank #3
- [Low Noise High Fidelity] New bee guitar cord with 22AWG oxygen-free-copper center conductors provides enhanced signal transfer, the PVC insulation material and the high-density stranded copper double shield provide noise rejection for quiet operation
- [Ideal for Choice] New bee 1/4 straight and right angle metal connectors, ensures a secure connection in any instrument, pedal, or amp jack. L shape great fro on stage guitar stands
- [Wide Compatible] Suitable for mixer, power amplifier, microphone, effector, decoder, equalizer, electoronic organ, electric guitar, electric bass and other electronic equipments. Widely used in the installation of smart home, karaoke speaker, professional stage audio, etc
- [Easy Disassemble] Making incidental repairs quick and easy! Very nice, flexible cable
- [Dont Hesite to Order] 24 hours customer services and professional technology team are standing by
Secure SMTP with TLS
Obtain a certificate from a trusted certificate authority for the SMTP hostname. The certificate file must contain the server certificate followed by the issuing chain in the order required by Postfix; the private key must not be world-readable. Typical Postfix settings are:
smtpd_tls_cert_file = /etc/ssl/mail/fullchain.pem
smtpd_tls_key_file = /etc/ssl/mail/privkey.pem
smtpd_tls_security_level = may
smtpd_tls_auth_only = yes
smtpd_tls_loglevel = 1
With smtpd_tls_security_level = may, server-to-server SMTP offers opportunistic STARTTLS. That is useful for broad Internet delivery because not every destination supports encryption. smtpd_tls_auth_only = yes prevents password authentication until TLS is active. For user submission, enforce encryption on port 587 rather than relying on clients to choose it.
Enable the submission service in /etc/postfix/master.cf by adding or uncommenting a service definition like this:
submission inet n - y - - smtpd
-o smtpd_tls_security_level=encrypt
-o smtpd_sasl_auth_enable=yes
-o smtpd_tls_auth_only=yes
-o smtpd_recipient_restrictions=permit_sasl_authenticated,rejectPort 25 is primarily server-to-server transport. Port 587 is the authenticated submission port for mail clients. If you offer another submission mode, document its TLS requirements and firewall rules explicitly. After changing master.cf, restart Postfix rather than only reloading it.
Recommended Free Tools
Publish DNS records that establish identity
DNS cannot guarantee inbox placement, but missing or contradictory records make delivery less trustworthy.
Rank #4
- Digital Family Calendar: BSIMB digital calendar wall touch screen puts an end to your chaotic life. Designed for busy families, the digital calendar keeps you organised and in step with your family. Assign different colours and tasks to each family member to make family scheduling easier and more intuitive.
- Easy Setup and Auto-Sync: Plug in, connect to WLAN and auto-syn your electric calendar in minutes. Digital wall calendar compatible with Google calendar, iCloud calendar, Outlook calendar, Cozi calendar and Yahoo calendar. Add events directly on the device or through the ecalendar app. Electronic calendar stays current whether you're at work or traveling—no manual updates needed.
- All-In-One Home Assistant: Smart calendar builds habits and encourage independence with personalised chores. Display daily meal plan to reduce the daily ‘What's for dinner?’ stress. To-do lists keep track of everything you want. Turning chores into valuable achievements with stars and rewards, making life easier and more enjoyable.
- Manage Anytime Anywhere: BSIMB electronic calendar for family stay connected with the powerful ecalendar app. Access and manage your digital wall calendar anytime, anywhere with free features like stars & rewards, photo screensaver, chore charts, meals plans, to-do lists etc. Electronic planner paid features like Magic Import tailor advanced tools for users with special needs.
- Stay in Touch with Loved Ones: Share photos or videos from your phone to electronic wall calendar with app, instantly update your life moment, and keep in touch with your family, especially those who are far away; you can also surprise your smart calendar digital wall by sending him a wish card; it's also great for keeping tech-illiterate elders in touch with the youngsters.
| Record | Purpose | What to check |
|---|---|---|
| A or AAAA | Maps the mail hostname to the VPS address. | mail.example.com resolves to the address actually used for SMTP. |
| MX | Identifies the server that receives mail for your domain. | The MX target is a hostname with an address record, not an IP literal. |
| PTR (reverse DNS) | Gives the sending IP a hostname. | The VPS provider has set the PTR to the same canonical mail name where possible. |
| SPF | Lists authorized sending sources for the domain. | The policy includes the VPS address or relay actually used, and there is one coherent SPF record. |
| DKIM and DMARC | Additional sender-authentication and policy signals used by many recipient systems. | Publish them when your chosen mail flow supports them and align their domains with your visible From domain. |
SPF is a DNS policy, not a setting inside Postfix. Write it to match the real path: adding an address that never sends mail creates confusion, while omitting a relay that does send mail causes SPF failures. Recipient requirements differ, so check the receiving domain’s current authentication expectations.
Configure firewalls and provider controls
Allow only the ports you use. A direct inbound and outbound mail host commonly needs TCP 25 for SMTP transport, TCP 587 for authenticated submission, and TCP 993 if Dovecot offers IMAPS. Do not expose plaintext IMAP or POP unless you have a specific, protected reason. Keep SSH restricted to administration networks where practical.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Some VPS providers block outbound port 25 by default or require a support request and a verified reverse-DNS entry. A technically correct Postfix setup cannot deliver directly while the provider drops the connection. Confirm the policy before troubleshooting application settings.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Test SMTP at the protocol level
Check the server greeting and capabilities
From a host that can reach the VPS, connect to port 25:
telnet mail.example.com 25At the SMTP prompt, identify the client:
ehlo mail.example.comA working server should return a multiline response containing 250-STARTTLS when TLS is available. Authentication capabilities may be hidden until TLS is negotiated, which is desirable. Do not send real credentials over an unencrypted test session.
Verify STARTTLS and authentication on submission
Use an SMTP client or an OpenSSL session against port 587 to confirm the certificate and encrypted handshake:
openssl s_client -connect mail.example.com:587 -starttls smtp -servername mail.example.comAfter the TLS handshake, issue EHLO mail.example.com again and inspect the capabilities. You should see 250-AUTH if Dovecot’s socket, Postfix SASL settings and the submission override are all working. A client can then authenticate and submit only to destinations permitted by your relay policy.
Inspect queue and logs
On Ubuntu, follow the mail log while performing a test:
sudo journalctl -u postfix -f
sudo journalctl -u dovecot -fUseful queue commands include:
mailq
postqueue -p
sudo postqueue -fLook for rejected destinations, DNS failures, TLS errors, authentication failures and repeated delivery retries. A message sitting in the queue is not proof of successful delivery; it means Postfix has not completed the next handoff.
Troubleshoot the failures that matter most
| Symptom | Likely cause | Action |
|---|---|---|
| Connection to port 25 times out | Provider block, firewall rule or service not listening. | Check provider policy, host firewall, ss -ltnp, and Postfix status. |
| Server says relay access denied | The recipient is outside mydestination and the client is not authenticated or trusted. |
Use port 587 with SASL, or correct the intended local destination. Do not remove reject_unauth_destination. |
| AUTH is absent after EHLO | TLS is not active, Dovecot’s socket path or permissions are wrong, or the submission override did not load. | Run the TLS test, inspect Dovecot and Postfix logs, verify the socket exists under Postfix’s chroot, then restart both services. |
| TLS handshake or certificate warning | Hostname mismatch, incomplete chain, expired certificate or unreadable key. | Use the exact SMTP hostname, install the full issuing chain in the required order, check expiry and correct file permissions. |
| Mail remains queued | DNS resolution failure, blocked outbound port 25, temporary recipient rejection or remote throttling. | Read the queue’s defer reason and logs, test DNS and connectivity, then resolve the stated cause before flushing the queue. |
| Messages reach spam | New or poor IP reputation, missing or misaligned sender authentication, reverse-DNS mismatch, complaint volume or content signals. | Verify PTR, forward DNS, SPF and any DKIM/DMARC policy required by recipients; send only wanted mail, monitor bounces and keep the host patched. |
Direct delivery versus an SMTP relay
Neither architecture is universally best. Compare the operational consequences before opening port 25.
Quick wins for a faster PC:
Scan for outdated or missing drivers - takes under a minuteDriver Scan →Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →| Decision factor | Direct Postfix delivery | SMTP relay |
|---|---|---|
| Control and data | Maximum control over queue, logs and message routing on your VPS. | Some routing and message handling occur on a separate provider. |
| Reputation | You build and protect the VPS IP and domain reputation yourself. | The relay supplies established infrastructure, subject to its policies and shared reputation model. |
| Deliverability monitoring | You must analyze rejection logs, bounces and authentication results. | The relay may provide dashboards and feedback, but you must still monitor your application and domain. |
| Network policy | Requires outbound port 25 access and correctly managed reverse DNS. | Often works when direct port 25 is restricted; you submit to the relay’s endpoint instead. |
| Cost and workload | No separate relay bill, but substantial patching, abuse response and reputation work. | Recurring cost or quotas in exchange for less mail transport maintenance. |
| Authentication support | You configure SPF, DKIM and DMARC tooling and key rotation. | You must align the relay’s SPF, DKIM and DMARC instructions with your domain. |
Operate the service safely
- Patch Ubuntu, Postfix, Dovecot and the operating system regularly.
- Use unique, strong credentials; disable or remove unused accounts; and protect SASL passwords and private keys.
- Monitor authentication failures, queue growth, outbound volume, bounces and repeated recipient rejections.
- Set sensible per-user or per-application sending limits so a compromised account cannot flood the Internet.
- Back up mailbox data and configuration, but protect backups as carefully as live mail because they contain credentials and private messages.
- Keep an abuse contact and a procedure for stopping compromised accounts or a runaway queue.
- Recheck DNS after address, hostname, provider or relay changes. An SPF record that was correct for one path may be wrong after routing changes.
Self-hosting SMTP is therefore an ongoing operations responsibility, not a one-time package install. A successful protocol test proves that a server can speak SMTP; it does not promise acceptance by every recipient or placement in an inbox.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
