If you try to add a Google Workspace mailbox to a sequencer by uploading an SMTP username and password, the connection fails with an error like 535-5.7.8 Username and Password not accepted. This is expected, and it isn't a problem with your mailbox.
Why the password upload fails
Google does not allow plain password authentication for Workspace accounts. Sequencers therefore cannot connect a Google Workspace mailbox from an SMTP/IMAP credentials list the way they can with a standard SMTP mailbox.
How to connect a Google Workspace mailbox
Before adding mailboxes, ensure that your sequencer is configured in the Maildoso settings.- In your sequencer, choose the Google / Gmail connection option rather than the generic SMTP or CSV upload option.
Sign in with the mailbox address when prompted, and authorise the sequencer.
You have full administrator access to your Google Workspace account. The mailbox password and the one-time code needed to complete sign-in are both available in your Maildoso dashboard — see Logging in to your Google Workspace mailboxes (password and one-time code).
Repeat for each mailbox, or use your sequencer's bulk Google connection flow if it offers one.
Alternatively, you can connect mailboxes directly from the Maildoso dashboard. Navigate to the Settings menu, go to the Sequencer section, and link your sequencer. Then, in the Email Accounts section, filter the list of mailboxes by selecting "Provider = Google," select the desired mailboxes, and click "Add to sequencer."
Connecting many mailboxes
Connecting dozens of Workspace mailboxes one by one is slow. You can connect multiple mailboxes directly from the Maildoso dashboard by filtering the Email Accounts section by "Provider = Google," selecting the desired mailboxes, and clicking "Add to sequencer." If this flow keeps failing part-way through, or your sequencer does not support bulk connections, contact us with the list of mailboxes and the sequencer you're using and we'll look at it with you.
What about SMTP mailboxes?
Standard Maildoso SMTP mailboxes are different — those do connect with a username and password, and can be uploaded to your sequencer as a credentials file. If an SMTP mailbox is rejected with a 535 error, the credentials themselves are worth re-checking before anything else.
Free Trial Limitations
During the free trial period, Maildoso does not support the use of Google Workspace mailboxes. The trial includes only SMTP mailboxes, and Google Workspace mailbox slots are not available. Note that new Google Workspace mailbox purchases are currently paused platform-wide (with no announced return date), so a Google-account bundle cannot currently be purchased via "Packages & Add-ons" even on a paid plan. SMTP mailboxes remain available for purchase and can be used with sequencers in the meantime; contact support to check whether your account already has unused Google Workspace slots.
A note on DKIM and SPF warnings
After connecting, some sequencers display a warning that DKIM, SPF, or DMARC is "not configured". Authentication for your Maildoso domain is set up and managed for you, and these warnings can generally be ignored — they reflect what the checker can see, not what is actually published.
If a mailbox still won't connect after following the steps above, contact us and we'll review your specific case. For a step-by-step Instantly walkthrough, see Connecting your mailboxes to Instantly, and for other connection errors across sequencers, see Troubleshooting sequencer connection errors.