Outages where Google Apps Email account can't pull down new messages via IMAP, but can still send over SMTP

Question

I've got 5 email accounts set up on my computer: 1 @gmail and 4 Google Apps for Business. Recently I've been getting an error with one of my Google Apps for Business accounts where it won't pull down any new emails. It will still send them, which is strange as the same application-specific password is used for both IMAP and SMTP.

The error has been showing up for the past week or so and its comes and goes at the rate of about one 12hr outage every 1-2 days.

During the outage I'm still able to view / receive new email via the web portal, but just not via any connected desktop / mobile mail clients.

The error is only happening on one of the accounts even though the other 4 are in the same Google Apps organization. The only thing I can think of that is different is that there are more users on this one account (3 users, with probably 10 or 12 devices). Where as the other accounts only have 1 or 2 users with 1-3 devices.

In the meantime as a work around I've setup diverts from the effected account to forward all incoming emails to another account which I can still view in a desktop mail client.

Any idea why this is happening and how I can resolve it ?

Background : All accounts are using IMAP to connect and all accounts have 2 step auth enabled with application-specific passwords used.

Answer 1

You are correct that the issue is because you have multiple users on that account. You're running into Google's IMAP limits.

From: https://support.google.com/mail/answer/97150?hl=en

If you have multiple users frequently accessing the same account or more than one IMAP client accessing Gmail at the same time, you may reach a connection threshold and receive the error message, 'Too many simultaneous connections.'

Gmail currently has a limit of 15 simultaneous IMAP connections per account.

IMAP and SMTP operate over different ports/connections, which is why you're still able to send, it's a different service (and also you wouldn't have many simultaneous connections to the SMTP server since that would only be opened when sending a message.)

As a possible workaround, if some of the devices are mobile devices, you could download the Gmail app (Android / iPhone) which supports multiple accounts (both personal and Google Apps will work) and won't count against your IMAP limit.