Before you start
Make sure the mailbox already exists in your 20i hosting account and that you know its current mailbox password. This is not necessarily the same password used to sign in to the hosting control panel. Have the complete address ready—for example, hello@yourdomain.co.uk.
Connect the iPhone to a reliable network and update iOS if an update is pending. If the account is already present but behaving incorrectly, record any locally stored drafts before removing it.
The quickest method: download the iOS profile
20i provides an Apple configuration profile for supported mailboxes. In Manage Hosting, open the relevant package, choose Email Accounts, find the mailbox, select Options and then Account Setup. Choose the iOS profile option and open it on the iPhone that will use the mailbox.
Follow the iPhone prompt to install the profile and enter the mailbox password when requested. A profile reduces typing errors, but some businesses prefer manual setup so every setting is visible. The manual instructions below use 20i’s standard Stackmail hostnames.
Add the account manually in current iOS
Open Settings, choose Apps, then Mail. Select Mail Accounts, Add Account, Other and Add Mail Account. On older iOS versions, Mail may appear directly in Settings; the labels are similar even when the route is shorter.
Enter your name, the full email address, mailbox password and a useful description such as Work email. Tap Next and select IMAP at the top. IMAP is preferable for most people because changes remain synchronised between the iPhone, webmail and other devices.
Enter the incoming mail settings
For Incoming Mail Server, use imap.stackmail.com as the host name. The username must be the full mailbox address, including everything after the @ symbol. Enter the mailbox password again even if iOS describes it as optional.
The secure IMAP port is 993 and SSL should be enabled. Apple Mail often detects this automatically. If it keeps verifying for a long time or displays an error, recheck the address and password before changing ports.
- Host name: imap.stackmail.com
- Username: your full email address
- Password: your mailbox password
- Port: 993
- Security: SSL enabled
Enter the outgoing SMTP settings
For Outgoing Mail Server, use smtp.stackmail.com. Enter the full email address and password again. Outgoing authentication is required; leaving those fields blank is a common reason an account can receive mail but cannot send.
20i supports SMTP port 465 or 587 with encryption. On iPhone, port 587 is a reliable starting point. If your network or configuration requires the alternative, use 465. Do not use an unrelated web-host name when the Stackmail hostname is available.
- Host name: smtp.stackmail.com
- Username: your full email address
- Password: your mailbox password
- Port: 587, or 465
- Security: TLS/SSL enabled
- Authentication: password
Save the account and test both directions
Tap Next and allow Apple Mail to verify the servers. Keep Mail enabled when asked which services to sync, then tap Save. Open the Mail app and locate the new mailbox.
Send a short test message to an address you can check separately, then reply to it. This confirms both outgoing and incoming mail. A successful incoming test alone does not prove that SMTP is configured correctly.
If the iPhone says it cannot verify server identity
Check that the hostnames are exactly imap.stackmail.com and smtp.stackmail.com. A custom hostname such as mail.yourdomain.co.uk can produce a certificate-name warning when its SSL certificate does not cover that address.
20i specifically recommends the Stackmail hostnames as a way to avoid certificate mismatch errors. Do not accept an unexpected certificate indefinitely without checking the server name; correct the hostname first.
If you can receive email but cannot send
Open Settings, Apps, Mail, Mail Accounts, select the account, then open Account and SMTP. Choose the primary server and confirm that it is enabled. Re-enter the full email address and mailbox password, enable SSL and confirm port 587 or 465.
Also check the Outbox for a message with a very large attachment or an invalid recipient. Try sending over a different network. If multiple devices fail with the same mailbox, reset or verify the mailbox password in 20i rather than repeatedly changing iPhone settings.
If the password is repeatedly rejected
Sign in to Stackmail webmail using the complete email address and the same password. If webmail also rejects it, reset the mailbox password through 20i. Updating the hosting control-panel password will not update an individual mailbox.
If webmail works, carefully re-enter the password in both the incoming and outgoing settings. Password managers and copied text can sometimes add a space. Delete the saved password completely before pasting or typing it again.
Choose sensible sync and notification settings
Once the account works, decide how often Mail should fetch messages and whether notifications are useful for that mailbox. Faster checking uses more battery and data. Shared or high-volume accounts may be easier to manage with selective alerts.
IMAP keeps folders and read status aligned, but deleting a message on one IMAP device can remove it from the server and other devices. Archive important mail according to the business’s retention needs rather than treating the phone as the only copy.
Stackmail iPhone settings at a glance
- Account type: IMAP
- Incoming server: imap.stackmail.com
- Incoming port: 993
- Incoming security: SSL
- Outgoing server: smtp.stackmail.com
- Outgoing port: 587 or 465
- Outgoing security: TLS/SSL
- Username: full email address on both servers
- Password: individual mailbox password
- Outgoing authentication: required
Common questions
What is my Stackmail username?
Your username is your complete email address, such as hello@yourdomain.co.uk. Use it for both the incoming IMAP server and outgoing SMTP server.
What are the Stackmail server names?
Use imap.stackmail.com for incoming mail and smtp.stackmail.com for outgoing mail. These official Stackmail hostnames also help avoid certificate-name mismatch warnings.
Which SMTP port should I use on iPhone?
Use port 587 with TLS as the first choice. 20i also supports port 465. Outgoing authentication must use the full email address and mailbox password.
Why can I receive emails but not send them?
The outgoing SMTP username or password is usually missing or incorrect, SSL is off, or the port is wrong. Check the primary SMTP server and re-enter all fields, even if iOS labels some as optional.
Will adding the account delete existing email?
Adding an IMAP account should synchronise mail stored on the server. If you are replacing an existing POP account or have local-only drafts, back those up before removing the old account.