Is SMTP service better for paid vs. free customers?

Is SMTP service better for paid vs. free customers?

I have been trying Zoho on the free tier for my small business (currently three employees, but we hope to grow), with the intent of checking it out before moving to a paid tier. For the most part, it has been very good, except for one small annoyance when sending e-mail, for which we use Thunderbird on Linux (Ubuntu and Arch) and Outlook on Windows 10. Here are the annoyances:

  • When sending from Outlook, sometimes the e-mail does not show up in the Sent folder for many minutes (up to an hour in the worst case). We don't know whether or not these e-mails show up immediately on the web or the e-mail app.
  • When sending e-mail from Thunderbird (both Linuxes), it occasionally hangs / times out copying e-mail to the Sent folder.
  • When sendind e-mail from Thunderbird on Arch Linux, it very occasionally just times out sending.

These problems are very intermittent (maybe once every hundred or couple hundred e-mails). But they are annoying when they happen. Is this something that willi improve when we move to a paid tier, or are the computing resources the same for the free and paid tiers? Thank you.