NexlyFlowSet up SMTP & verify your domain
6 steps · About 8 minutes
What you will finish with. Your own business mailbox connected to NexlyFlow, tested, saved and ready to send campaigns from your own domain.
Who this is for. Every new account – this is the first thing to do after signing up.
Before you start, have ready: your business email address, its SMTP host and port, the encryption type your provider requires, your mailbox password (or an app password if your provider uses two-factor login), and – if you want replies detected – the IMAP host and port.
1Collect your mailbox details
Log in to your email provider dashboard and find the outgoing mail (SMTP) settings. Every provider publishes these in their help pages. Write down the host, the port, the required encryption, and the username – the username is usually your full email address, not just the part before the @.
Find your settings by provider
Click the company that hosts your business email. These are the values those providers publish – if your provider shows something different in your own account, use theirs.
Not listed? Search your provider name plus the words SMTP settings – every provider publishes these on their own help site. If you get stuck, send us the provider name and we will look it up with you.
Why this matters. These values must match your provider exactly. NexlyFlow connects as an email client would, so a single wrong character or a mismatched port and encryption pair will be refused by the mail server.
Expected result. You have four values written down: host, port, encryption, username – plus the password you will use.
If it fails. If your provider only shows settings labelled for Outlook or Apple Mail, use those same values – they are the same SMTP settings.
2Open the Sending Setup page
In the NexlyFlow app, click Sending Setup in the left menu. On a phone, open the workspace menu at the top, then Sending Setup. This page holds every mailbox connected to your workspace.
Why this matters. All sending configuration lives on one page, so you never have to hunt through settings.
Expected result. You see the SMTP form with fields for host, port, username, password and the sender identity.
If it fails. If you cannot see the left menu on a phone, scroll to the top of the page – the workspace menu collapses on small screens.
3Fill in the SMTP fields
Enter the values you collected. Each field does a specific job:
Why this matters. From name and From email are what your recipient actually sees – a real person at a real company gets replies; a no-reply address does not. Port and encryption must be a matching pair, because the server refuses a plain connection on a secure port and vice versa.
Expected result. Every field is filled and no field shows a red validation warning.
If it fails. The values above are format examples only – always use the exact values your own provider publishes. Do not guess a port.
4Test the connection
Click Test connection and wait a few seconds. NexlyFlow opens a real connection to your mail server and authenticates with the credentials you entered – nothing is sent to anyone.
Why this matters. Testing before saving means you never discover a broken mailbox halfway through a campaign. It also tells you which half is wrong: an authentication error points at username or password, while a connection or timeout error points at host, port or encryption.
Expected result. A green Connection successful message appears.
If it fails. Authentication failed: re-type the password (pasting often carries invisible spaces) and use your FULL email as username; if your provider uses two-factor login you must generate an app password. Connection or timeout error: the host, port or encryption is wrong – try the alternative port your provider lists, with its matching encryption.
5Save and enable the mailbox
Once the test succeeds, click Save SMTP settings. Saving stores the mailbox; it then becomes selectable for campaigns in your workspace. If you edit these settings later, leaving the password field blank keeps the stored password.
Why this matters. A saved-but-untested mailbox is the most common cause of a campaign that silently sends nothing. Saving only after a green test keeps that from happening.
Expected result. The mailbox appears in your mailbox list and can be picked when you create a campaign.
If it fails. If saving appears to do nothing, re-run the test first – the form keeps you from saving credentials that have not passed.
6Turn on reply detection (IMAP)
Find the Reply detection toggle on the same page and switch it ON. NexlyFlow immediately performs a live connection test to your inbox; the toggle only stays on if that test succeeds. Leave the IMAP override fields empty unless your incoming server differs from your SMTP host – in that case enter the IMAP host and port your provider gives you.
Why this matters. SMTP only sends. Reading replies needs IMAP – without it, a lead can reply and you would never see it in your Pipeline, so warm leads go cold.
Expected result. The toggle stays ON and replies start appearing in Pipeline within a few minutes of arriving.
If it fails. If the toggle flips back off, the inbox test failed: check the IMAP host and port, and remember that changing your mailbox password requires toggling reply detection off and on again to re-authenticate.
Send us the exact error message you see and we will identify it for you. Contact support – we reply within 1 business hour.
Custom tracking domain (one CNAME)
track.yourdomain.com, link.yourdomain.com or go.yourdomain.com.www — that would break your website.CNAME (not TXT, not A)track — only the prefix. Do not type the full track.yourdomain.com. Cloudflare and Route 53 are the exception: they want the full name.trk.nexlyflow.com — exactly this, no http://, no spaces.Open and click tracking
In Campaigns you will find two checkboxes: Disable open tracking and Do not rewrite links. They apply to every campaign in this workspace and take effect on emails sent from that moment on.
Open tracking works by adding one invisible 1×1 image to your email. Click tracking works by replacing each link with a redirect that passes through our tracking domain first. Tick a box and that piece is simply not added — your email goes out without it.
If your open and click rates read 0%, that is not a bug. It means tracking is switched off for this workspace. Untick the boxes in Campaigns and future sends will report again — emails already sent stay untracked.
Keep tracking ON when
- Your sending domain is established — months of sending, steady replies, no spam-folder history.
- You have set up your own custom tracking domain (the CNAME step above). Links then run on your domain, not a shared one.
- You are testing subject lines and want open rates as a rough relative comparison between two versions.
- You are writing to people who already know you, or who opted in.
- You need click data to judge interest or to decide who deserves a follow-up.
Keep tracking OFF when
- Your domain or mailbox is new and warming up (roughly the first 4–8 weeks). This is the single most common case.
- You are sending genuine cold outreach to people who have never heard of you.
- You already have a deliverability problem — mail landing in spam, or an unusually low reply rate.
- You have not configured a custom tracking domain, so links would point at a shared one.
- Your recipients sit in privacy-sensitive or regulated industries (law, finance, government, EU/GDPR).
- You write plain-text-style emails, where a hidden image and rewritten links look out of place.
Why open rate is a weak number anyway. Apple Mail Privacy Protection preloads images for every message it receives, so an Apple recipient is counted as having opened your email whether they read it or not. On a Singapore B2B list that is a large share of your contacts.
The metric that actually tells you whether cold outreach is working is the reply rate — and replies are counted without any tracking at all.
Simple rule: keep both boxes ticked while you are warming a new domain. Once the domain is established and you have your own tracking domain in place, untick them if you want the data.