Email Notifications

Technical requirements for connecting your inbox to HubSpot using IMAP

Last updated: January 23, 2019

To connect your inbox to HubSpot, your email server must support IMAP (Internet Message Access Protocol) and SMTP (Simple Mail Transfer Protocol). Below you'll find the requirements for connecting your inbox using IMAP.

This article has technical resources and definitions meant for your IT team or your email administrator. If your email server is not currently set up for IMAP, please work with your IT administrator to make sure your inbox is configured correctly.

Please note: the conversations inbox does not support an IMAP connection. If you are trying to connect an email account to the conversations inbox, you need to connect an inbox that is hosted with either Gmail or Office 365.

Server requirements

When you connect your inbox to HubSpot and send emails, HubSpot connects with your email server over TLS (Transport Layer Security). To access the inbox and submit mail, IMAP and SMTP are used, respectively. Both ports running these protocols must be open to traffic, or you may whitelist the IPs making these connections. 

There are certain encryption methods that have become de facto best practice for certain ports. For example, if you wish to connect via IMAP using 143, you must upgrade the connection with STARTTLS to TLSv1.2 (preferred) or TLSv1.0, TLSv1.1, or SSLv3.

The following graphic outlines supported ports and corresponding encryption methods:  

 Preferred  Supported  Not Supported
 993 TLSv1.2  TLSv1.0, TLSv1.1, SSLv3

 SSLv2, plaintext,

 any STARTTLS upgrade 

 143 STARTTLS TLSv1.2  STARTTLS upgrade to
 TLSv1.0, TLSv1.1, SSLv3
 TLS, SSLv2, plaintext 
 587 STARTTLS TLSv1.2  STARTTLS upgrade to
 TLSv1.0, TLSv1.1, SSLv3
 SSLv2, plaintext 
 465 TLSv1.2  - STARTTLS upgrade to 
 TLSv1.0, TLSv1.1, SSLv3   - TLSv1.0, TLSv1.1, SSLv3

 SSLv2, plaintext,

 any STARTTLS upgrade

 25 STARTTLS TLSv1.2  STARTTLS upgrade to
 TLSv1.0, TLSv1.1, SSLv3
 TLS, SSLv2, plaintext 

If none of the above ports are open or if the open ports do not have the correct TLS encryption protocol, you will not be able to connect to your inbox. Ask your IT department about opening the right ports in your server and/or adding the right TLS encryption to the open ports.


Your email configuration can affect your ability to connect your inbox via IMAP. If you have different usernames and passwords for your IMAP and SMTP servers, you will not be able to connect with IMAP, as this configuration is not supported at this time. Other configuration information to note:

  • Logging in with different credentials for each server will be supported in the near future.
  • IMAP must be enabled in order to sync mail.
  • ActiveSync protocol is not supported at this time.

Security certificate

In the case that your SSL certificates are not signed by a Certificate Authority, there is an option to allow a non-secure certificate when initiating the connection. You'll need the appropriate username and password to access your server as well as the IMAP and SMTP server names. Follow these instructions to obtain this information or work with your IT team to determine the correct login credentials to use. 


Your IT team might only allow certain IP addresses to connect with your inbox. If this is the case, your IT team will need to whitelist the IP addresses HubSpot uses to connect your inbox. You must contact HubSpot Support to get these IP addresses.  

Please note: if you're trying to connect your inbox via generic IMAP and continually receive UNAUTHORIZED errors, it’s likely there is a firewall or another security filter blocking HubSpot from connecting to the mail server. To resolve this, you must whitelist the HubSpot IPs making the SMTP/IMAP connection. Contact HubSpot Support to obtain these IP addresses.

Because authentication methods, security settings, and available protocols can differ from one email server to another, it may be necessary to work with your IT team to confirm that your email server meets the above requirements. If you experience any difficulty during the IMAP connection process, work with your IT team or administrator when you open a ticket with HubSpot Support, as your IT department can provide specific information needed to troubleshoot that HubSpot does not have access to.