UCM 6200 - emails deferred - gmail account


I have 2 UCMs and both had the voicemail to email function working using gmail.com email accounts.
Noticed that both of them since June,2022 have “deferred” emails.

both UCM have different gmail.com accounts.
i checked the password for accounts by logging on the gmail.com from web browser.
Base fw:

just wondering if there is something changed on UCM 6200’s or Gmail.com for this behavior.
hope to get some help.


GMail has changed the account policy, you need to create a special pswd for the APPs,
search the web


excellent! Thank you:+1:

figured it out.
I had to turn on 2 form authentication for google account, then the App Password option was available.
once done, it gave a new password, applied that to UCM SMTP setting and emails are working.

This topic helped me setup and troubleshoot.


I have just set up 2fa. Still getting a deferred send result. Tried it with the smtp.gmail.com:587 and without the 587. Any suggestions?


Never mind. Just started working. Have a good weekend


GMail for security reasons no longer accepts “normal” SMTP, but you have to create pswd for APP as indicated by the link:



Thank you for your response.


I have the same issue but in 2023, everything it is setted up like these posts but I have no success the only thing that I am missing os an option that said that access to low security apps must be enabled but this option it is not available anymore in google.
Software V:

I am trying to upgrade but for some reaon i can’t, i’ll keep trying.


The access that Google is allowing in 2023 is to create an App Password. You cannot create an App Password until you enable 2-Factor-Authentication (2FA) on that Gmail account. A consideration for the future is that when you change the password of the Gmail Account then the App Password will be deactivated and must be re-generated.

The above is working fine for my UCM emails.



Thank you RickL, I’ve done that already, I have the same setup for a CRM email service wqhich is working ok, but I cannot make gmail work with my grandstream.



I also have thesettings in my grandtream as follows same as the configuration in the suggested posts. “mydomain.com” is hosted by gsuite.
Server: smtp.gmail.com:587
User Name: myemail@mydomain.com
Pass: “App password from google”


Your first big clue to the problem is shown in your list of the Gmail App Passwords. I do not know your language, so I looked at my Gmail account to understand what you are showing. Your App Password named Grandstream has never been used. That is the first problem for you to solve.

The two most likely problems are:
1a. The UCM email settings need to be using a mail client and not sending the email messages directly.
1b. Something is mis-spelled in the settings for the UCM’s email. It could be either the User Name or the Password. For those fields I prefer to do a Copy & Paste instead of typing by hand.
2. Something in your router or firewall is blocking the UCM from talking to Gmail.

As soon as you get the UCM to log into your Gmail account then you will see in the Gmail account that the App Password named Grandstream has been used. After that you can proceed with making sure the server & port are correct.

When the UCM has an outgoing email message that has a status of deferred, then the UCM will try to send that message again, I think around 25 attempts. You can click on the little Information button on that message to see the activity. When you get the UCM email to work then you may get a bunch of those deferred messages that are finally sent out.



Hello Rick, I have revoked the last password, and double checked spelling on both email account, server+port and generated a new password app and copy and pasted it, but I am still getting defered message.
Ther is no gmail restriction that i know on this network, as well as firewall. I have setted this up again from scratch but the app seems not to be using the password also.


You still need to get the UCM to be able to log into the Gmail account, before you can work on getting the emails to send.

Here are the settings that I am using in my UCM -> System Settings -> Email Settings:
TLS Enable = checked
Type = Client
Email Template Sending Format: = HTML
SMTP Server = smtp.gmail.com:465
Enable SASL Authentication = checked
Username = [myaccount]@gmail.com
Password =
Enable Email-to-Fax = not checked
POP/POP3 Server address =
POP/POP3 Server Port =
Display Name = PBX Messages
Sender = [myaccount]@gmail.com

Since you are using Gsuite you might need a few differences in those settings. Refer to Gsuite for those details.

I do not know if I can help you further.

  1. Is your CRM service/server located on the same physical network as the UCM? If yes then you know you have a good path from your network to Gmail, if no then you may have something in your network that the UCM cannot reach Gmail. You could test this by setting up a email client on a computer (Thunderbird is a free email client), create a new Gmail App Password, and use that for testing.
  2. You can try doing a network packet capture on the UCM at Maintenance -> Network Troubleshooting -> Ethernet Capture. This is where you might see an error message coming back from Gmail. The problem with this is that the messages will be encrypted. In the Email Settings you can turn off the encryptions TLS & SASL (which means emails certainly will not work) and maybe you will be able to get an error message that points you towards the solution.
  3. If this seems more technical than what you want to do, you may need to get a local consultant that is an expert on computer networks.
  4. You could investigate changing the UCM to use MTA to send the email messages directly. You might be able to go through Gsuite to get that to work, or you might be able to use SMTP Relay through Gsuite.