weMail doesn’t send emails, email sending API does. The APIs you have connected with weMail, they have a sending limit. you have connected one of the six email sending APIs (Mailgun, Elastic Mail, SMTP, SES, SparkPost, and PostMark) with weMail.
When the sending limit is reached, API will not allow you to send emails. And that’s when weMail will send an email that the quota has exceeded and we will disable the option for you.
How to resolve this? Get in touch with your API provider and increase the sending limit.