Use Your Own SMTP Provider with TrekMail
Connect and reuse an SMTP provider for a whole domain or one business From address linked to Gmail, Outlook, or another inbox.
Article details
Type, difficulty, plans, and last updated info.
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Article details
Type, difficulty, plans, and last updated info.
- Type
- Guide
- Difficulty
- Beginner
- Plans
- Nano · Starter · Pro · Agency
- Last updated
- Aug 15, 2026
A custom SMTP profile lets a domain send through a provider you already use, such as Amazon SES, SendGrid, Mailgun, Mailjet, or another SMTP service. You save the provider details once in TrekMail, then choose that profile for the domains or eligible sending addresses that should use it.
When a custom profile helps
Use a custom profile when you need to keep an established provider's sender setup, reporting, or delivery controls. It is also the sending option for a Nano domain, because Nano does not include Managed TrekMail SMTP.
It is not a way to bypass TrekMail safeguards. Mail submitted through TrekMail still needs an active domain, an authorized sender, an available mailbox, and must pass TrekMail's account safety and rate checks. Your provider can impose additional limits or reject a sender that it has not verified.
What you need before you start
Prepare these details from the provider's own SMTP setup page:
- SMTP hostname
- Supported port and encryption method
- SMTP username
- SMTP password or SMTP-specific API credential
- The provider's sender-domain verification, SPF, DKIM, and any return-path instructions
TrekMail accepts custom-profile ports 465, 587, and 2525. Port 465 requires implicit SSL/TLS; do not pair it with STARTTLS. Use a secure provider connection whenever one is offered. Never paste dashboard credentials, a mailbox password, or a general cloud access key when the provider gives you a separate SMTP credential.
Add and test a profile
- Open Domains, choose a domain, then open SMTP.
- Select New custom SMTP profile.
- Enter a recognisable profile name and the values from your provider.
- Select the encryption that matches the provider's instructions.
- Select Test connection. Correct any error before saving.
- Save the profile and send a small real message to an address you control.
The connection test checks that TrekMail can reach and authenticate with the provider. It does not prove that the provider accepts every From address or that recipient providers will place the message in the inbox. The real test message should confirm both.
Choose where the profile is used
Custom SMTP is normally selected per domain.
| Goal | Where to make the change |
|---|---|
| Route all ordinary addresses on one domain through a provider | Domains → select the domain → SMTP |
| Reuse the same provider on another domain | Select the saved profile from that domain's SMTP tab |
| Set the route that new domains inherit | Select the route, then choose Make this the account default |
| Replace routes on all existing domains | Use Apply to all domains only after reviewing the impact |
| Give an eligible extra From address a different provider | Webmail Settings → Sending addresses |
Saved profiles belong to the account, not to one domain. Editing a profile changes it everywhere it is used. Before editing or deleting one, open its usage details and note every affected domain and sending address.
Mail apps should still use the IMAP and SMTP settings shown in that mailbox's Apps & devices screen. Do not put your custom provider's password into every Outlook or phone setup. TrekMail receives the authenticated submission, then applies the domain or sending address route safely behind the scenes.
DNS and sender verification
Your external provider must be allowed to send for the domain. Complete the provider's own sender verification first, then add the records it gives you at the DNS provider.
- Keep a single SPF TXT record for the domain. Add the provider's authorised mechanism to that existing record instead of creating a second SPF record.
- Add the provider's DKIM records exactly as supplied. Do not guess a selector or reuse a selector from a different provider.
- Check the domain's DMARC policy after SPF and DKIM are passing.
- Send a test to a mailbox you control and inspect the authentication result there.
TrekMail's DNS screen is still useful for the mail-hosting records that TrekMail manages. It cannot replace the external provider's sender-verification instructions. For a DNS refresher, see Required DNS Records.
Common problems
| What you see | Likely cause | What to do |
|---|---|---|
| Test connection fails | Wrong host, port, encryption, or SMTP credential | Copy the current values from the provider's SMTP page and test again |
| The provider rejects the From address | The sender or domain has not been verified at the provider | Complete that provider's sender-domain verification |
| Messages fail before reaching the provider | The TrekMail domain is inactive, no route is selected, the mailbox cannot send, or a safety limit applies | Check Domains, the mailbox, and the dashboard notices |
| SPF or DKIM does not pass | The provider's DNS records are missing or conflict with existing records | Compare the provider's records with the live DNS zone; keep one SPF record |
| A profile change affects unexpected domains | The profile is shared | Review the profile's usage before editing; create a separate profile when the settings must differ |
Editing or deleting a profile safely
Changing a profile updates every domain and Send As address that uses it. Test a replacement profile before changing a shared one.
When you delete a profile, TrekMail removes that profile from the domains and sending addresses that used it. A paid-plan domain can fall back to Managed TrekMail SMTP; a Nano domain can become not configured for sending until you assign another working profile. Check each affected domain immediately after deletion and send a test message.
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