How to test sending over email over 50Mb

Hi All, I need to test an email gateways blocks email that are over 50Mb in size. I don’t have my own mail server to use. Does anyone know a email server that will send emails over 50Mb?

Hello @thebluepill2!

I would check that the configuration for blocked email had that rule. This seems to be a functionality of the gateway and I would expect that the maker of the gateway had already evaluated that.


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Thanks Joe,

I more need to test the rule is in place, by sending an email over 50Mb through the gateway. Also to see what notification are sent to users when the email is blocked.

Hello @thebluepill2!

I reviewed your new post and re-read your initial post. This may be more of a testability challenge than a testing challenge.

When you ask about an email server with a capability of sending large emails, I think of a couple of things. If I think of an “email” as a subject and body, I would find challenging the believe that an email of 50 Mb would ever be created. In that sense, the risk of that scenario is small, and I wouldn’t create a test case for it. If I think of an “email” as a subject, body, and attachments, then I believe it is possible to see emails of 50 Mb (and more) in size. For this response, I’ll assume an email with subject, body, and attachments.

If I understand the scenario, you are interested in the behavior of the email gateway for at least two email sizes: one is less than a threshold and one is greater than the threshold. If your primary information objective is the behavior of the gateway around a threshold, then you have a testability challenge rather than a testing challenge.
I submit the threshold does not matter. I recommend changing the threshold (or collaborating with someone who can change the threshold) to something very small. In that case, your scenarios will demonstrate that the rule executes, and, as mentioned in your second post, you can review the notification.

Lastly, I wanted to explore risk around the scenario. One component of risk is the likelihood of something happening. If the average size of an email in the production environment is small, then the scenarios above may not be of much value. If the average size of email approaches the gateway threshold, then I would want to understand the business intent of blocking these emails.


Hello @thebluepill2

I’m aware that you currently don’t have an email server to use but I think that the easiest way to test this requirement would be to build an email server on the outside of your mail gateway (but it may be costly in time). This email server should only connects to the edge of your email gateway. From here you can test this function works (as well as other functions like checking that your Antivirus functions) without being impacted by external companies impacting your results.


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Thanks Joe, you are correct in your assumptions. The email is total size and is assumed to include attachments, with the two cases, above and below the threshold.

Your recommendation of changing the threshold limit is what I am exploring and will likely be the way I test this.

Appreciate the time taken to answer my questions