Email Group Size Limit in Gmail Account

I periodically send group email messages to a list of about 160 recipients. Usually I do this directly from the Gmail website using Firefox on Windows 10, and I’ve never had a problem related to the size of the group. Several months ago I added my Gmail account to eM Client, which I had been using prior to that only for another email address from my Internet provider. I really like being able to read messages from both email accounts in a common inbox and to easily send messages from either account using the same program. Today I tried to send a message to a group of 158 addresses using eM Client. An error message was returned that began with the following:

Your message did not reach some or all of the intended recipients.
 
The following recipient(s) cannot be reached:

xxxxx@xxx.net’ - 4.5.3 Your message has too many recipients. For more information regarding
4.5.3 Google’s sending limits, please visit:
4.5.3  https://support.google.com/mail/?p=TooManyRecipientsError f10sm2789942pju.34 - gsmtp

yyyyyy@yyy.com’ - 4.5.3 Your message has too many recipients. For more information regarding
4.5.3 Google’s sending limits, please visit:
4.5.3  https://support.google.com/mail/?p=TooManyRecipientsError f10sm2789942pju.34 - gsmtp

There were actually 58 recipients listed rather than just the two above, and they were the last 58 in my list. That implies that the message was sent successfully to the first 100 addresses in the list. I’ve checked with a sample of those 100, and they did indeed get the message.

I re-sent the message to only the last 58 in a separate message right afterward, and that seemed to work.

Question: Why would Gmail have an address limit when using the eM Client interface but not when using the native interface?

Gmail has an SMTP mail limit of 100 recipients. That means when sending using an email client like eM Client or any other, you cannot send to more that 100 recipients in one message.

Webmail is not SMTP, so does not have the same restrictions.

Thanks for confirming that limit, Gary. I suspected something like that. With my latest experience of trying to send to 158 recipients and having 58 rejected, then being able to re-send to those 58 right afterward, I’m guessing that in the future I might be able to send to 80 and 78 in back-to-back messages. I prefer composing in and sending from eM Client rather than Gmail webmail because if eM’s superior formatting capabilities.