Overview
Link your mailboxes with Apollo to gain full functionality of core engagement tools like emails, sequences, conversations, meetings, and more. Your linked mailboxes send your emails on Apollo. You can unlink your mailboxes from Apollo at any time.
While Gmail is the preferred mailbox provider (MBP) to get the most out of Apollo's functionality, Apollo supports many different mailbox providers and custom email servers. For a list of supported MBPs and standards, sneak a peek at supported mailbox providers.
Manage mailboxes and domains to create and manage mailboxes and domains in Apollo. Admins can review mailbox and domain health across the team. If you're not an admin, Apollo shows your linked mailboxes and related deliverability info.
Check out the following steps to link your mailboxes on Apollo.
Link Your Mailbox
Did you know? If you need additional mailboxes, you can generate domains and mailboxes directly on Apollo. Customize your domain, assign email addresses to team members, and reach out with no costly or complicated set up required!
To link your mailbox to Apollo:
- Launch Apollo and click Settings > Email setup and health.
- Click Mailboxes, then click Link mailbox.
Apollo doesn't support Google groups. Linking a Google group to Apollo results in an error. Use an individual mailbox instead.
- Click Gmail or Outlook, and check to agree to Apollo's terms of service. Then click Link mailbox.
- If you're already signed in to your email account, select the account that you want to link. Otherwise, enter your email address and password to sign in. Review and agree to the permissions required.
When you connect an email or calendar account to Apollo, the permissions apply only to the specific person who authorizes the connection. Apollo can send email, sync email activity, and sync calendar activity only for the mailbox that you connect.
For Outlook mailboxes, Apollo uses delegated permissions. Apollo doesn't use application permissions to access every mailbox in your tenant.
Each person must sign in and consent to connect their own mailbox.
To understand how Apollo uses data, review How data sharing works on Apollo.
Your mailbox has now been linked. Apollo recommends that you continue to configure your mailbox to avoid deliverability issues.
Repeat these steps to link additional mailboxes.
- (Optional) To link an alias, return to Mailboxes management. Click … beside the mailbox, then click Refresh aliases.
Next, configure your mailbox on Apollo to ensure your messages are compliant and consistent.
The number and type of mailboxes you can link depend on your Apollo plan:
- Basic: Link up to 1 mailbox per user.
- Professional: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 5 custom IMAP or SMTP mailboxes per user.
- Organization: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 15 custom IMAP or SMTP mailboxes per user.
If you have reached your mailbox limit, upgrade your plan or unlink a mailbox before linking another. If your team uses a legacy Apollo plan, your limits may differ. Check your plan details in Apollo for the limits available to your team.
- Click Other and enter your email address. Check to agree to Apollo's terms of service. Then click Link mailbox.
- If you use a mailbox provider that Apollo recognizes, such as Yahoo or iCloud, Apollo redirects you to your email provider sign-in. Follow the steps to sign in to your account.
- If Apollo can't determine the mailbox type, select your email provider or click See all providers.
- Follow the steps to sign in.
- Alternatively, click Custom IMAP settings to log in with IMAP, then enter your mailbox credentials, which should include:
- Email address
- Email password
- IMAP host
- Port number
- SMTP host
- If you're unsure where to find these credentials, contact your email mailbox provider for help. Once you've added your credentials, click Log In.
You have now connected your mailbox to Apollo. Apollo recommends that you continue to configure your mailbox to avoid deliverability issues.
To ensure that your linked mailbox doesn't encounter issues sending emails, monitor the deliverability score and follow Apollo's recommendations to adjust your settings or behavior.
Repeat these steps to link additional mailboxes.
The number and type of mailboxes you can link depend on your Apollo plan:
- Basic: Link up to 1 mailbox per user.
- Professional: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 5 custom IMAP or SMTP mailboxes per user.
- Organization: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 15 custom IMAP or SMTP mailboxes per user.
If you have reached your mailbox limit, upgrade your plan or unlink a mailbox before linking another. If your team uses a legacy Apollo plan, your limits may differ. Check your plan details in Apollo for the limits available to your team.
Troubleshoot Mailbox Linking
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Troubleshoot |
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| Why can't I connect my mailbox? | How do I configure my email if I use Microsoft Exchange or a custom IMAP provider? | Why does Apollo say my email isn't linked even though it shows as connected? |
| How do I resolve OAuth error code 04112? | ||
Why can't I connect my mailbox?
There could be a few different culprits. Check the following to resolve the connection error:
- Check your email address
- Amend your POP/POP3 settings
- Check with your colleagues
- Request Microsoft admin approval
- Turn your Gmail on
- Check your domain settings
- Check the error status (non-Gmail)
- Check your mailbox folder
Check your email address
Apollo doesn't support email addresses that contain the following characters:
example--domain.comexample..domain.comexample@.domain.comexample.@domain.comexample-@domain.comexample@-domain.com
Connect a different mailbox if your email address includes any of these characters in the email name or domain.
Some new Microsoft mailboxes, and Microsoft mailboxes on free licenses, may return error Spam Block/Bounce - Rejected code 550 5.7.708 when you send email from Apollo. If this happens, contact Microsoft Support to request an IP exception.
Amend your POP/POP3 settings
If you use Nylas Mail to link your mailbox, Nylas Mail doesn't support connecting to mailbox accounts via POP/POP3. Check with your mailbox provider to see if your domain is set up under POP/POP3 as default. The vast majority of mailbox providers who support POP3 also support IMAP, and you can connect to Apollo with IMAP. Nylas also supports SMTP.
Check with your colleagues
You can only link each unique mailbox to one Apollo instance at a time. If you or your team have already linked your mailbox to another Apollo account, you need to unlink it from the first account before you can connect it to a different one.
Request Microsoft admin approval
If you encounter an admin approval error when you try to link a Microsoft 365 mailbox, your organization likely requires administrator consent before you can connect Apollo.
Depending on your organization's Microsoft settings, use one of the following options:
Request approval
- From the Microsoft consent screen, click the option to request approval.
- Enter a reason that you need to connect Apollo, then submit the request.
- Wait for your Microsoft administrator to approve the request.
- After the request is approved, return to Apollo and link your mailbox again.
The option to request approval only appears if your organization has enabled Microsoft's admin consent workflow. If you don't see the option, contact your Microsoft 365 administrator directly.
Ask a Microsoft administrator to grant consent
Your Microsoft 365 administrator can grant consent to Apollo directly:
- Sign in to the Microsoft Entra admin center.
- Go to Entra ID > Enterprise apps > All applications.
- Search for and select Apollo.
- Click Permissions.
- Review the permissions that Apollo requests, then click Grant admin consent.
After an administrator grants consent, return to Apollo and link your mailbox again.
To review the delegated permissions Apollo requests for an individual Outlook mailbox, check out What permissions does Apollo request for Gmail and Outlook mailboxes?
For more information, check out Grant tenant-wide admin consent to an application on Microsoft Learn.
Turn your Gmail on
If you encounter an error when you try to link a Gmail mailbox, your team's Google admin may have turned off the Gmail service for your account.
To resolve the issue:
- Contact your Google Workspace admin to enable the Gmail service for your account, then follow the steps above to connect your account with Apollo.
- If the issue persists, contact Google Workspace Support to inspect your account.
For more information, check out Control Gmail Access For Your Organization's Users on Google Support.
Check your domain settings
If Apollo routes you to a Google login page when you're trying to link a non-Gmail mailbox:
- Ask your IT admin to remove the following TXT record from your domain name system (DNS) records:
v=spf1 a mx include:_spf.google.com - Then try to link the mailbox again.
Check the error status (non-Gmail)
If you connect a non-Gmail mailbox to Apollo and encounter an error, check out Nylas Support to find the specific cause of the error.
If you're still having issues connecting a mailbox to your Apollo account, support is only a message away! Reach out to Apollo support for more help.
Check your mailbox folders
Nylas Mail, a third-party mailbox provider, uses UIDValidity to sync mailboxes. Some custom account or server configurations can lead to inconsistent UIDValidity, affecting sync consistency. If the UIDValidity of your mailbox changes, Nylas attempts to resync the original value until too many failures cause it to stop. When this happens to a mailbox that you link with Apollo, Nylas disconnects it.
To prevent this from happening:
- Ensure each folder in your email account has at least one message in it.
- Delete all empty folders in your email account.
How do I configure my email if I use Microsoft Exchange or a custom IMAP provider?
Follow these instructions to link your mailbox and input your server settings manually. Ensure that IMAP and SMTP are enabled on your email server, and have the necessary server addresses, ports, and authentication details ready. If you're uncertain about these settings, consult your IT administrator or email service provider for assistance.
Why does Apollo say my email isn't linked even though it shows as connected?
This discrepancy often arises when there's a sync issue between Apollo and your email provider. It may appear connected, but authentication can expire or permissions might change, affecting the link. To resolve this, unlink and then re-link your mailbox.
How do I resolve OAuth error code 04112?
Apollo may display Your request has timed out or is invalid (Error Code 04112). Please try again during an authorization flow. This error means that the authorization state expired or couldn't be read. It can occur if the authorization flow takes more than five minutes.
Error code 04112 isn't specific to one provider. It may appear when you authorize Google, Microsoft, Gmail, or another supported connection during login, signup, mailbox linking, calendar linking, or a similar authorization flow.
To resolve the error:
- Return to the action you were completing in Apollo.
- Start the authorization flow again and complete the prompts.
You have now restarted the authorization flow.
Error code 04112 doesn't mean that administrator approval is required. If Microsoft displays an admin-consent request, follow the separate Request Microsoft admin approval guidance in this article.
If the error continues, check Apollo's status, then reach out to Apollo support. Include the exact error message, the action you were attempting, your provider and account type, the time the issue started, and a screenshot of the OAuth error.
Want some hands-on help? Join Apollo's live webinar session, Email Deliverability 101, to learn the ABCs of linking your mailbox, setting up domains for maximum deliverability, and monitoring the health of your email performance.
FAQs
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Frequently asked questions |
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| What are the benefits of linking my mailbox to Apollo? | What does linking my mailbox to Apollo actually do? | Which mailbox providers does Apollo support? |
| How many mailboxes can I link, and how do sending limits work for each? | Will Apollo read my emails? | How does Apollo use my linked mailbox for sending and syncing emails? |
| If I change my email password or it expires, do I need to re-link my mailbox? | As an admin, can I review setup for my team's mailboxes and domains? | What permissions does Apollo request for Gmail and Outlook mailboxes? |
| Can I use an email alias on Apollo? | ||
What are the benefits of linking my mailbox to Apollo?
Linking your mailbox unlocks Apollo's full engagement suite: automated sequences, email tracking, reply detection, and CRM syncing. This integration streamlines your outreach, ensuring every interaction is logged and actionable. For SDRs and AEs, it means less manual work and more time engaging prospects.
What does linking my mailbox to Apollo actually do?
When you link your mailbox, Apollo connects directly to your email provider, allowing you to send emails through Apollo while maintaining your email's authenticity. This ensures that your outreach appears as sent directly from your inbox, enhancing deliverability and trust.
Which mailbox providers does Apollo support?
Supported mailbox providers (MBPs): Apollo's mailbox functionality works best with Gmail. However, Apollo also supports linking to other mailbox providers through Nylas Mail, a third-party provider.
Apollo doesn't support shared mailboxes. To successfully link a mailbox to Apollo, use an individual mailbox with its own credentials.
Nylas Mail supports:
- Microsoft Exchange
- Office 365
- Outlook
- Yahoo!
- Custom email accounts/servers
Nylas also supports SMTP. Nylas doesn't support large transactional sending services like Mandrill or Amazon SES. For that reason, Apollo doesn't support linking to those services. Additionally, Nylas doesn't support mailbox accounts connected via POP/POP3. The vast majority of mailbox providers who support POP3 also support IMAP, and you can connect to Apollo with IMAP.
Nylas is unable to work reliably with mailboxes hosted on SiteGround because SiteGround consistently blocks some Nylas IP addresses. This can lead to repeated timeouts and authentication failures when trying to link a SiteGround-hosted mailbox to Apollo.
This is a known SiteGround limitation, not an issue with your mailbox credentials or Apollo configuration. SiteGround's firewall may treat third-party app connections like Nylas as malicious activity, and Nylas has been unable to resolve this limitation with SiteGround.
If your provider isn't supported, you can generate domains and mailboxes directly on Apollo. Customize your domain and assign email addresses to team members without costly or complicated set up.
As you scale, protect your email deliverability rates. If you send a higher volume of emails, review Apollo's recommended email sending limits. For more email deliverability best practices, read Chapter 7 of Apollo's book Outbound Sales.
How many mailboxes can I link, and how do sending limits work for each?
The number and type of mailboxes you can link depend on your Apollo plan:
- Basic: Link up to 1 mailbox per user.
- Professional: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 5 custom IMAP or SMTP mailboxes per user.
- Organization: Link unlimited Google Workspace and Microsoft 365 mailboxes, plus up to 15 custom IMAP or SMTP mailboxes per user.
If you have reached your mailbox limit, upgrade your plan or unlink a mailbox before linking another. If your team uses a legacy Apollo plan, your limits may differ. Check your plan details in Apollo for the limits available to your team.
Each mailbox has its own sending limits — both those determined by your email provider and those set on Apollo. Apollo recommends starting with 50 emails per day per mailbox to maintain deliverability. Linking multiple mailboxes can help scale your outreach while staying within safe sending thresholds. Check out Configure Email Sending Limits to learn more.
If you link your mailbox using Nylas Mail, you may experience a mailbox linking limit not associated with Apollo. This can occur even if you're within your Apollo mailbox limit. Unlinking does not immediately reset the limit, as recent connections may still count toward your usage window, and limits typically reset per calendar month. As a workaround, you can relink the same mailbox to use until the reset or temporarily use a Gmail or Microsoft mailbox. Contact Nylas support to learn more.
Will Apollo read my emails?
Apollo periodically scans emails to detect replies to outbound messages sent through Apollo and to log activity on the relevant contact. Apollo doesn't manually read the content of email communications or manually collect any data from customer systems. Learn more about how Apollo respects your data.
How does Apollo use my linked mailbox for sending and syncing emails?
When you use Apollo to send emails, they are sent through your linked mailbox, ensuring messages come from your actual email address. This allows Apollo to sync sent emails and track opens, clicks, and replies, providing outreach insights.
If I change my email password or it expires, do I need to re-link my mailbox?
Yes, if your email password changes or expires, you need to re-authenticate your mailbox in Apollo. This ensures continuous access and functionality. Check out how to link your mailbox.
As an admin, can I review setup for my team's mailboxes and domains?
Yes, you can manage mailboxes and domains as an admin for an overview into your team's mailbox and domain setup. Identify and resolve sending issues to keep your team's emails hitting inboxes instead of spam.
What permissions does Apollo request for Gmail and Outlook mailboxes?
When you sign up or log in with Google or Microsoft, Apollo requests basic identity permissions.
When you link a mailbox, Apollo requests additional email, calendar, and directory permissions for the mailbox that you connect.
For Microsoft 365, Apollo uses delegated permissions for the specific mailbox owner. Apollo doesn't use application permissions for every mailbox in your tenant.
Gmail
| When Apollo requests it | Scope | What it lets Apollo do |
|---|---|---|
| Sign up or log in | https://www.googleapis.com/auth/userinfo.email |
Confirm your email address. |
| Sign up or log in | https://www.googleapis.com/auth/userinfo.profile |
Confirm your basic profile information. |
| Full mailbox link | https://mail.google.com/ |
Access Gmail and IMAP data for the mailbox that you connect. |
| Full mailbox link | https://www.googleapis.com/auth/calendar |
Read and write calendar data for meetings and scheduling. |
| Full mailbox link | https://www.googleapis.com/auth/directory.readonly |
Read your Google Workspace directory for mailbox and meeting workflows. |
Outlook
| When Apollo requests it | Scope | What it lets Apollo do |
|---|---|---|
| Sign up or log in | openid |
Confirm your identity. |
| Sign up or log in | profile |
Confirm your profile information. |
| Sign up or log in | user.read |
Read your basic Microsoft account details. |
| Sign up or log in | offline_access |
Keep the mailbox connection active after you sign in. |
| Full mailbox link | email |
Access your email address information. |
| Full mailbox link | mailboxsettings.read |
Read mailbox settings that support mailbox configuration. |
| Full mailbox link | calendars.readwrite |
Read and write calendar data for meetings and scheduling. |
| Full mailbox link | mail.send |
Send email from the mailbox that you connect. |
| Full mailbox link | contacts.readwrite |
Read and write contact data used in mailbox workflows. |
| Full mailbox link | mail.readwrite |
Read and write mailbox data for the mailbox that you connect. |
| Full mailbox link | people.read |
Read relevant contact data used in mailbox workflows. |
Can I use an email alias on Apollo?
Email aliases share the DNS settings, sender reputation, and email sending limits of the connected mailbox. Apollo supports email aliases, but Apollo can't track replies sent to an alias or update a contact's status based on those replies.
Before Apollo can detect a Gmail alias, configure it as an address that the linked mailbox can send from:
- For Gmail, go to Settings > See all settings > Accounts and Import or Accounts. Under Send mail as, click Add another email address, then add and verify the alias. This requirement applies to both Google Workspace and personal Gmail accounts. For Google Workspace, creating the alias only in the Google Admin console isn't sufficient.
After you configure the alias in Gmail, link the mailbox to Apollo or click Refresh aliases for an existing linked mailbox. Apollo supports automatic alias refresh only for Gmail and Google Workspace mailboxes. Microsoft 365, Outlook.com, and other mailbox providers don't support automatic alias refresh.
To remove an alias, check out Google Support.
- Microsoft 365 mailbox aliases are available only on paid Apollo plans. Reach out to Apollo support if you need this feature enabled on your paid Apollo plan. Microsoft 365 mailbox aliases are available on paid Apollo plans. After you add or update an alias in Microsoft 365, return to Mailboxes in Apollo and click ... beside the connected mailbox, then click Refresh aliases. If Apollo doesn't display the alias after you refresh, confirm that the alias is configured on the connected Microsoft 365 mailbox and that your Apollo plan supports aliases.
Next Steps
With your mailbox connected, follow these next steps to set yourself up for success:
| Configure Your Mailbox on Apollo | After you link your mailbox to Apollo, configure your mailbox settings to keep your outbound consistent and protect deliverability. |
|---|---|
| Use Email Warmup | Use email warmup to help build a positive sender reputation and signal to mailbox providers that your emails are safe and trustworthy. |
| Configure Email Sending Limits | Typically, your mailbox provider has email sending limits. You can also set Apollo-specific sending limits. Apollo recommends starting with conservative sending limits—such as 50 emails per day and 6 per hour—to maintain a strong sender reputation. Exceeding these limits can negatively impact deliverability. |
| Join the Apollo Community | Ask questions, swap tips, and connect with other Apollo users to grow your knowledge and solve problems faster together! |