Unable to Connect IMAP Email – ‘SMTP Settings Incorrect’ Error
SOLVE
Hi everyone,
I’m having major trouble connecting my standard IMAP email account to HubSpot. No matter what I do, HubSpot returns: “SMTP settings incorrect.”
Here’s everything I’ve already checked/tried:
My hosting company has confirmed the server addresses and ports:
IMAP: 993, 143
SMTP: 465, 587, 25
Username is the full mailbox (confirmed correct).
Server address is 100% correct.
No two-factor authentication (2FA) enabled for these mailboxes.
No special app passwords required/used.
No IP restrictions or firewalls blocking HubSpot—confirmed by host.
These exact settings work with other mail clients (Outlook, Apple Mail, Thunderbird, etc.).
I have even tried HubSpot’s “Allow non-secure certificate” setting just in case, with no luck.
Additional details:
The error is persistent and happens only with HubSpot—not when using the same credentials in other apps.
The mailbox provider says everything is standard on their side and nothing is being blocked.
No concurrent session or connection limit errors appear.
I’ve hit a wall and would appreciate any insight, especially if anyone has encountered this with IMAP/SMTP before on HubSpot. Are there HubSpot-specific SMTP authentication requirements or quirks I might be missing?
Unable to Connect IMAP Email – ‘SMTP Settings Incorrect’ Error
SOLVE
From my experience, HubSpot’s IMAP/SMTP integration can be a bit finicky even when all standard settings seem correct. A few things I’ve seen cause persistent SMTP settings incorrect errors:
First, HubSpot sometimes requires the exact port and encryption combination. For SMTP, 465 with SSL or 587 with TLS is usually the safe choice, HubSpot doesn’t always auto-detect SSL vs TLS correctly. Even if your provider allows multiple ports, HubSpot may fail if the combination isn’t what it expects.
Second, username format matters. Even if your host accepts just the local part of the email, HubSpot almost always needs the full email address as the username. Make sure there are no extra spaces, typos, or hidden characters.
Third, some email hosts (like Office365, Gmail, and certain cPanel setups) require SMTP authentication separately from IMAP login. HubSpot needs a successful SMTP handshake to connect, so check that the My SMTP server requires authentication option is being used if it exists.
Finally, HubSpot sometimes caches failed attempts. If you tried multiple incorrect combinations, disconnecting and reconnecting the mailbox, or even clearing browser cache and trying from a fresh login, can help.
If none of this works, the last workaround I’ve seen is creating an app-specific password, even if your provider says it’s not required. HubSpot sometimes fails with certain hosts unless this is set up.
Unable to Connect IMAP Email – ‘SMTP Settings Incorrect’ Error
SOLVE
From my experience, HubSpot’s IMAP/SMTP integration can be a bit finicky even when all standard settings seem correct. A few things I’ve seen cause persistent SMTP settings incorrect errors:
First, HubSpot sometimes requires the exact port and encryption combination. For SMTP, 465 with SSL or 587 with TLS is usually the safe choice, HubSpot doesn’t always auto-detect SSL vs TLS correctly. Even if your provider allows multiple ports, HubSpot may fail if the combination isn’t what it expects.
Second, username format matters. Even if your host accepts just the local part of the email, HubSpot almost always needs the full email address as the username. Make sure there are no extra spaces, typos, or hidden characters.
Third, some email hosts (like Office365, Gmail, and certain cPanel setups) require SMTP authentication separately from IMAP login. HubSpot needs a successful SMTP handshake to connect, so check that the My SMTP server requires authentication option is being used if it exists.
Finally, HubSpot sometimes caches failed attempts. If you tried multiple incorrect combinations, disconnecting and reconnecting the mailbox, or even clearing browser cache and trying from a fresh login, can help.
If none of this works, the last workaround I’ve seen is creating an app-specific password, even if your provider says it’s not required. HubSpot sometimes fails with certain hosts unless this is set up.
