Application Errors

If MailMerge365 will not start, the message it shows ends with an error code such as (Error code MM-05.), along with a link to the matching section of this page. Find your code below for what it means and what to do about it.

Underneath the message there is a Technical details box with a Copy technical details button. You do not need to understand what it says. If you end up contacting us, send that text along and it tells us exactly what went wrong.

Try this first

Most startup problems clear up with one of these, so it is worth trying them before anything else.

  1. Refresh the add-in. Click the white space inside the MailMerge365 pane to select it, then press Ctrl + R (Cmd + R on a Mac). This reloads the pane and clears its cache.
  2. Start over from a new email. Close the pane, close the email you were writing, open a new one, and start MailMerge365 again.
  3. Restart Outlook. If you use Outlook in a browser, sign out of your mailbox and back in, or open it in a private window with your browser extensions switched off.

If the error comes back, look up its code below.

Error codes

MM-01 – MailMerge365 could not start sign-in

MailMerge365 could not start the Microsoft sign-in component at all. This is nearly always about the version of Outlook you are using or your network, not about your account.

What to do

  1. Refresh the add-in with Ctrl + R (Cmd + R).
  2. Check that Outlook is up to date. MailMerge365 needs a current version of Microsoft 365 for Windows or Mac, or Outlook in a browser. Older standalone versions such as Outlook 2016 are not supported.
  3. If your company restricts what add-ins can reach, ask your IT department to allow login.microsoftonline.com and mailmerge365.com.
  4. Restart Outlook and try again.

If it still fails, send us the technical details. They tell us which version of Outlook you are on, which is usually the answer here.

MM-02 – Sign-in could not be completed

The Microsoft sign-in window opened, but Microsoft did not sign you in. The decision came from Microsoft, so the reason lies with your account or your organization's settings.

Why this happens

  • Sign-in was cancelled, or a different account was selected by mistake.
  • MailMerge365 has not yet been approved for your organization.
  • A security policy is blocking the sign-in, for example because the device is not managed, multi-factor authentication is required, or you are on an unexpected network.
  • You signed in with a personal Microsoft account. MailMerge365 works with work and school accounts (Microsoft 365) only.

What to do

  1. Try again and select your work or school account.
  2. If you see a message about needing approval, your Microsoft 365 administrator has to approve MailMerge365 once for the whole organization. Send them this section and they will know what to do.
  3. If you are working from a personal device or an unusual location, try again from your normal work computer, or ask your IT department which policy is stopping the add-in.

If it still fails, send us the technical details. They include the reference number Microsoft gave for the refused sign-in, which your administrator can look up directly.

MM-03 – The sign-in window could not open

Neither the sign-in pop-up nor the backup sign-in window could open or finish. This is a browser or window problem rather than a problem with your account.

What to do

  1. Switch off pop-up blockers for Outlook, and allow pop-ups from login.microsoftonline.com and mailmerge365.com.
  2. Let the sign-in window finish. It closes by itself once you are signed in, so do not close it yourself.
  3. Allow cookies, including third-party cookies, if you use Outlook in a browser. Privacy extensions, tracking protection and "block third-party cookies" settings all stop the sign-in window from working.
  4. If you use more than one screen, move the Outlook window to your main display and try again. The sign-in window can otherwise open off-screen where you cannot see it.
  5. Refresh the add-in with Ctrl + R (Cmd + R) and try once more.
  6. If you use Outlook in a browser, try a different browser, or a private window with extensions switched off.

MM-04 – Sign-in finished without signing you in

The sign-in window closed, but MailMerge365 was not given anything to sign you in with. This is uncommon and usually means the window was interrupted right at the end.

What to do

  1. Refresh the add-in with Ctrl + R (Cmd + R) and sign in again, letting the window close on its own.
  2. Use Sign out at the bottom of the pane, then sign in again and select your account.
  3. Restart Outlook.

MM-05 – Outlook could not save your draft

You were signed in successfully, but Outlook would not save the email you are working on. MailMerge365 has to save it before it can start, because that is how it keeps track of your campaign. There is nothing wrong with your account or your licence.

MailMerge365 already tries again a few times on its own, so if you see this message the save failed repeatedly, or Outlook never answered at all. Once you have worked through the steps below, press Try again underneath the message rather than starting over.

Why this happens

  • You switched to another email, or closed the one you were writing, while signing in. MailMerge365 works on the email that was open when you started it.
  • The add-in was started from an email you received rather than from a new message, a reply or a forward.
  • Outlook is offline or is having trouble reaching your mail server.
  • The draft cannot be saved: it is too large, an attachment is causing trouble, or your mailbox is full.
  • You are writing from a shared mailbox that you do not have permission to save drafts in.

What to do

  1. Open a new email, or a reply or forward, start MailMerge365 from there, and leave that email open until it has finished starting.
  2. Check that Outlook is online. In Outlook for Windows, look for Working Offline on the Send / Receive tab.
  3. If your email has attachments, try without them first and add them once MailMerge365 has started.
  4. Check that your mailbox is not full.
  5. If you are sending from a shared mailbox, check with your IT department that you have permission to send from it.

If it still fails, send us the technical details. They tell us exactly what Outlook objected to.

MM-06 – Your draft was saved but could not be read

Outlook saved your email, but then did not give MailMerge365 the information it needs to carry on.

What to do

  1. Refresh the add-in with Ctrl + R (Cmd + R).
  2. Start again from a new email.
  3. Restart Outlook.

This one usually points to a problem at our end, so please do send us the technical details even if the steps above get you going again. It helps us fix it properly.

MM-07 – MailMerge365 could not be reached

Signing in worked, but the add-in could not reach the MailMerge365 service afterwards.

What to do

  1. Check that you are still online by loading any other web page.
  2. Wait a minute and refresh the add-in with Ctrl + R (Cmd + R). The service may have been briefly unavailable.
  3. On a company network, ask your IT department to allow mailmerge365.com through the firewall, proxy or web filter.
  4. If you use a VPN or privacy extensions, switch them off temporarily and try again.

If it still fails, send us the technical details. They show whether your request reached us at all.

MM-08 – Your account could not be connected

MailMerge365 reached the service, but your account could not be connected. The message shown above the error code tells you why. Here is what each one means.

"Not linked to Office365" or "Not connected to Office365"

Setup has not been finished for this account, or the connection to Microsoft 365 has expired, which typically happens after a password change. Follow the setup steps the add-in offers and sign in again when Microsoft asks you to.

"We could not reach Microsoft to verify your sign-in."

MailMerge365 has to check your sign-in with Microsoft, and could not reach them just then. This is usually a brief network problem and nothing is wrong with your account. MailMerge365 retries a couple of times by itself, so if you are seeing this message those retries did not help either. Press Try again underneath the message. If it keeps happening, check whether anything on your network, such as a VPN or a web filter, is blocking login.microsoftonline.com.

"Authentication for Office365 failed. Please login again."

The permission MailMerge365 had for your mailbox is no longer valid. Use Sign out at the bottom of the pane, then sign in again.

"Could not create folder for bounce detection."

MailMerge365 keeps a folder in your mailbox to collect emails that bounce back, and it could not create it. Look for a folder called MailMerge365 in your mailbox, near the Junk Email folder, and delete it. Then press Try again underneath the message.

"Could not create rule for bounce detection."

MailMerge365 could not create the inbox rule that files bounced emails into that folder. Usually this means your mailbox has reached Outlook's limit on how many rules it can hold, or your organization does not allow add-ins to create them. Delete any rules you no longer use, then press Try again underneath the message. If that does not help, get in touch with us.

MM-09 – Your sign-in was not accepted

Microsoft signed you in, but MailMerge365 could not accept the sign-in, twice in a row. This is nearly always an out-of-date sign-in stored on your computer.

What to do

  1. Use Sign out at the bottom of the pane, then sign in again.
  2. Refresh the add-in with Ctrl + R (Cmd + R).
  3. Check that your computer's clock and time zone are correct. If the clock is more than a few minutes out, a perfectly good sign-in looks expired.
  4. Restart Outlook.

If it still fails, send us the technical details. They show when the sign-in expired, and they contain nothing sensitive.

MM-10 – Too many sign-in attempts

MailMerge365 stopped after several sign-in attempts in quick succession, so that you are not left in a loop of sign-in windows. It has cleared everything it had stored on your computer, so a fresh start usually works.

What to do

  1. Close the pane and open it again from a new email.
  2. Refresh the add-in with Ctrl + R (Cmd + R).
  3. Switch off pop-up blockers and allow cookies, as described under MM-03. A blocked sign-in window is the usual reason for the repeated attempts.
  4. Restart Outlook.

Still stuck?

Get in touch at help@mailmerge365.com and include:

  • The error code, for example MM-05.
  • The technical details, using the Copy technical details button underneath the message.
  • Which Outlook you use: Outlook for Windows, Outlook for Mac, or Outlook in a browser.

The technical details describe your version of Outlook and what failed. They never contain your email content, your recipients or your password.

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