Send Form Emails From Your Own Domain (Custom SMTP, 2026)

By default, form backends send email from their own infrastructure — something like notifications@splitforms.com. That's deliverable and fine for most sites. But there are two good reasons to send from you@yourdomain.com instead:

• Brand and trust. An auto-responder from your own domain reads as a message from your company, not from a form tool. Leads reply to it more, and corporate spam filters treat established domains with history better than shared sending addresses.
• Deliverability ownership. When you send through your own SMTP, your domain builds (and keeps) its own sender reputation. You're not sharing a reputation pool with every other user of a service, and you can take that reputation with you if you ever move providers.

For agencies the case is stronger still: client forms should send from the client's domain, full stop.

The feature is designed around one principle: switching to your own SMTP must never cost you an email. Four mechanisms enforce that:

• Encrypted storage. Your SMTP password is encrypted with AES-256-GCM before it's written, and is never displayed back in the dashboard — you can overwrite it, but not read it.
• Test-before-activation. Custom SMTP doesn't go live until you click Send test email and a real message is delivered through your server. A typo in the host or port can't silently break your forms. Editing any part of the config resets verification, so you always re-test after changes.
• Everything switches together. Once verified, both auto-responder emails and owner notification emails send from your address with your From name.
• Automatic fallback. If your SMTP server is unreachable, rejects credentials, or times out, splitforms immediately retries through its own infrastructure. The email still arrives — from the splitforms address — so a server outage on your side never means a lost lead notification.

1. Upgrade to a paid plan (Pro, $5/month, or the 3-Year plan) if you haven't — custom SMTP is a paid feature.
2. Open Settings → Email notifications → Send from your own domain (SMTP).
3. Enter your SMTP host and port, and choose whether the connection uses SSL/TLS (port 465) or STARTTLS (port 587).
4. Enter your username (usually your full email address) and password — for Gmail and Microsoft 365, an app password, not your login password.
5. Set the From email and From name recipients will see, e.g. hello@yourdomain.com and Acme Studio.
6. Click Send test email. When it arrives, the config is verified and activates. Every form email now sends from your address.

That's the whole flow. The remaining work is DNS — SPF/DKIM/DMARC — covered below.

Gmail / Google Workspace

Google no longer accepts your account password for SMTP. You need an app password: enable 2-Step Verification on the account, then generate an app password at myaccount.google.com/apppasswords.

Host:     smtp.gmail.com
Port:     465 (SSL) or 587 (STARTTLS)
Username: you@gmail.com (or you@yourdomain.com on Workspace)
Password: the 16-character app password
From:     the same address as the username

Note Gmail rewrites the From header to the authenticated account — send from the account you want recipients to see.

Outlook / Microsoft 365

Host:     smtp.office365.com
Port:     587 (STARTTLS)
Username: you@yourdomain.com
Password: an app password (requires MFA + security defaults
          allowing app passwords; many tenants need an admin
          to enable SMTP AUTH for the mailbox)
From:     the same mailbox address

The most common failure here is the tenant blocking SMTP AUTH — if the test email fails with an auth error on known-good credentials, ask your Microsoft 365 admin to enable "Authenticated SMTP" for that mailbox.

Transactional providers (ZeptoMail, Resend, SMTP2GO, …)

Purpose-built transactional email services are the best option at any real volume: higher sending limits than Gmail/Outlook, proper bounce handling, and first-class SPF/DKIM tooling. Create an API-key-style SMTP credential in the provider's dashboard and plug it in:

ZeptoMail:  smtp.zeptomail.com    : 465/587
Resend:     smtp.resend.com       : 465/587 (user "resend")
SMTP2GO:    mail.smtp2go.com      : 2525/587/465

Username/password: the SMTP credential from the provider's dashboard
From:              an address on a domain verified with that provider

With these providers, the From domain must be one you've verified in their console — which conveniently forces the SPF/DKIM setup you should be doing anyway.

DNS authentication is your responsibility— only you control your domain's DNS. Without these records, mail from your domain via a third-party SMTP relay is a spam folder candidate:

Your SMTP provider's docs list the exact values to paste. After DNS propagates, send a test and check the headers — you're looking for spf=pass, dkim=pass, and dmarc=pass.

• Test email fails with an auth error — you're using your login password instead of an app password (Gmail/M365), or SMTP AUTH is disabled for the mailbox (Microsoft 365 tenants).
• Test fails with a connection error — wrong port/SSL combination. 465 expects implicit SSL; 587 expects STARTTLS. Some hosts block 587 outbound — try 465.
• Verified, but emails land in spam — SPF/DKIM/DMARC missing or misaligned with the From domain. Check the received message headers for spf= and dkim= results.
• Emails arrive from splitforms again — the automatic fallback kicked in because your SMTP server rejected or timed out. Check your provider's status page and sending limits, then re-run the test email.
• Edited the config and now it's inactive — by design: any change resets verification. Click Send test email again to re-activate.

Questions? Email hello@splitforms.com — we respond within a few hours.

• Custom auto-responder emails (HTML + CSS) — design the email your domain sends.
• Form backend vs email service — where splitforms ends and SendGrid-style tools begin.
• Receive form submissions by email — notification deliverability deep dive.
• Docs: auto-responders & custom sending domain
• Sign up free — 500 submissions/month, upgrade for custom SMTP.