Rackspace Email SMTP Settings
Rackspace Email: hosted mailboxes on the emailsrvr.com platform, billed per user.
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Outgoing mail (SMTP)
SMTP server
secure.emailsrvr.com
Port. STARTTLS
587
Port. SSL/TLS
465
Security
SSL/TLS on 465 (recommended) or STARTTLS on 587.
Incoming mail (IMAP)
IMAP server
secure.emailsrvr.com
Port. SSL/TLS
993
Port. STARTTLS
143
Incoming mail (POP3)
POP3 server
secure.emailsrvr.com
Port. SSL/TLS
995
Port. STARTTLS
110
Sending limits & login
Daily send limit
Per-mailbox hourly and daily caps apply (Rackspace throttles bulk sending).
Authentication
Sign in with your full email address and mailbox password.
App password
No app password. Manage the mailbox password in the Rackspace Cloud Office control panel.
All three protocols share the single host secure.emailsrvr.com.
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Rackspace Email SMTP, IMAP and POP3 settings
Rackspace Email is a standalone mailbox service, separate from Rackspace's cloud hosting and from its Hosted Exchange and Microsoft 365 offerings. Everything runs on secure.emailsrvr.com, and Rackspace now documents only the encrypted ports. Its sending limit is unusual: 10,000 recipients per address per 24 hours, counted by recipients rather than by messages, and the counter resets at midnight US Eastern rather than in your own timezone.
For incoming mail, use the IMAP server secure.emailsrvr.com on port 993, or POP3 at secure.emailsrvr.com on port 995. Pick the exact values from the tool above and copy them straight into your mail client.
Checked against Rackspace Email's own documentation: docs.rackspace.com, postmaster.apps.rackspace.com. Ports and limits change, so check there too if something will not connect.
Rackspace Email settings at a glance
One card with every server and port on it. Right click to save it, or share the page and this is the preview people see.
What to enter as your Rackspace Email username and password
Wrong credentials, not a wrong port, are the usual reason a Rackspace Email connection fails. These are the exact values to type.
Your full email address, for example you@yourdomain.com
Your Rackspace mailbox password, entered as a normal password (no OAuth, no app password)
Get your email passwordHow to set up Rackspace Email in a mail client
The exact path through Rackspace Email's own settings, in order.
- 1
Get the mailbox password from your account admin
Rackspace mailboxes are created and reset by the account administrator in the Cloud Office control panel. End users sign in to webmail at https://apps.rackspace.com.
- 2
Set the incoming server
secure.emailsrvr.com on port 993 with SSL for IMAP, or port 995 with SSL for POP3. Rackspace recommends IMAP.
- 3
Set the outgoing server
secure.emailsrvr.com on port 465 with SSL. This is the only outgoing setting Rackspace's current documentation lists.
- 4
Sign in with the whole address
The username is the full email address including the domain, using normal password authentication. Rackspace's Thunderbird guide leaves the method on Autodetect, which resolves to Normal Password.
- 5
Keep simultaneous connections low
Rackspace asks that any one sending client hold no more than five concurrent connections to its servers.
What Rackspace Email looks like filled in
Every mail client asks for the same handful of fields. Here they are with Rackspace Email's values already in place.
Account settings: Rackspace Email
Server
secure.emailsrvr.comPort
465Encryption
SSL/TLSAuthentication
RequiredUsername
Your full email address, for example you@yourdomain.comPassword
Your Rackspace mailbox password, entered as a normal password (no OAuth, no app password)Server
secure.emailsrvr.comPort
993Encryption
SSL/TLSAn illustration of the fields, not a screenshot of any one app. Field names differ slightly between Outlook, Apple Mail and Thunderbird; the values do not.
Rackspace Email SMTP settings in Thunderbird
The outgoing server dialog with Rackspace Email's details entered. Outlook and Apple Mail ask for the same four things under slightly different names.
Which port should you use for Rackspace Email?
SSL/TLS on 465 (recommended) or STARTTLS on 587.
STARTTLS
Starts as a plain connection, then upgrades to an encrypted one. The modern standard for sending.
SSL/TLS
Encrypted from the first byte. Widely supported and a good choice when 587 is blocked.
Plain SMTP
Meant for server-to-server relay. Home networks and cloud hosts block it, so do not use it to send from a client.
Why your Rackspace Email connection is failing
The failures people actually hit with Rackspace Email, and what fixes each one.
The sending machine is holding too many simultaneous connections to Rackspace. Cut it to five or fewer and send again.
Rackspace counts recipients, not messages: 10,000 recipients per address per 24 hours. One message to 200 people spends 200 of the allowance. The window runs 00:00:00 to 23:59:59 US Eastern.
A Rackspace mailbox accepts 400 messages in any 10 minute window and defers anything beyond that. Nothing is lost; the sending server retries.
Rackspace caps a message at 50 MB including headers, body and attachments. Share a link rather than attaching the file.
Rackspace's outbound servers use TLS opportunistically and fall back to plaintext if the receiving server refuses it. Your connection to Rackspace is encrypted; the onward hop may not be.
Rackspace Email sending limits
The daily cap counts recipients rather than messages and resets at midnight US Eastern; receiving is separately throttled to 400 messages per mailbox per 10 minutes.
Per day
10,000 recipients per email address per 24 hours
Max attachment
50 MB per message including headers, body and attachments
Rackspace Email quirks by mail client
Thunderbird
Rackspace's own Thunderbird guide leaves authentication on Autodetect for both incoming and outgoing, which resolves to Normal Password after you click Re-test.
Sending cold email through Rackspace Email
Per-mailbox hourly and daily caps apply (Rackspace throttles bulk sending). Sign in with your full email address and mailbox password.
Those caps make single-mailbox sending fine for personal mail but a poor fit for cold outreach at volume. Emailchaser spreads sending across warmed inboxes and manages deliverability, so you can scale without burning Rackspace Email accounts.
Other business email and web hosting
Setting up more than one mailbox? These sit in the same category as Rackspace Email.
Common questions about Rackspace Email SMTP settings
What are Rackspace Email's SMTP settings?
Rackspace Email's outgoing (SMTP) server is secure.emailsrvr.com. Use port 587 (STARTTLS) or 465 (SSL/TLS). SSL/TLS on 465 (recommended) or STARTTLS on 587. Sign in with your full email address and password (or app password).
What is Rackspace Email's IMAP or POP3 server?
Rackspace Email's incoming IMAP server is secure.emailsrvr.com on port 993 (SSL/TLS). If you prefer POP3, use secure.emailsrvr.com on port 995.
Which port should I use for Rackspace Email?
Use port 587 with STARTTLS wherever it's offered, it's the modern standard for authenticated sending. Port 465 with SSL/TLS is a solid alternative. Avoid port 25, which most networks block for client sending. Rackspace Email's recommended value is above.
Why won't my Rackspace Email SMTP connection work?
Check authentication first: Sign in with your full email address and mailbox password. No app password. Manage the mailbox password in the Rackspace Cloud Office control panel. Then confirm the host, port and security method match exactly, a 587/SSL or 465/STARTTLS mismatch will fail to connect.
Can I send bulk or cold email through Rackspace Email?
Not at scale. Per-mailbox hourly and daily caps apply (Rackspace throttles bulk sending). Providers throttle bursts to fight spam, so pushing cold email through one mailbox hits limits and wrecks deliverability. High-volume outreach belongs on dedicated infrastructure that spreads sending across warmed inboxes, which is what Emailchaser does.
Does Rackspace still support the old non-SSL ports 110, 143 and 25?
Its current settings page lists only the encrypted options on secure.emailsrvr.com: IMAP on 993, POP3 on 995 and SMTP on 465. Older guides that mention plain ports are out of date. Set your client to SSL and use those three.
Is Rackspace Email the same as Rackspace Hosted Exchange or Microsoft 365 from Rackspace?
No. Rackspace Email is Rackspace's own mailbox platform on emailsrvr.com. Hosted Exchange and Microsoft 365 are separate products Rackspace also resells, with different server names and different rules. A guide written for one will not work for the other.
Why does one big send eat my whole day's allowance?
Rackspace measures the limit in recipients, not messages. A single message with 5,000 addresses in Bcc spends 5,000 of your 10,000. If you regularly mail lists, put them through a bulk sending service and keep Rackspace for person to person mail.
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