App Engine for Java utilizes the Mail API to allow your applications to send e-mail
messages programmatically. Although the measurements you see in Table 2-5 carry
their own metrics, each also contributes to the request-level metrics that
encompass these detailed line items. For example, outgoing data over the Mail API
will increase your outgoing bandwidth measurements. Table 2-5 shows the
specifics for the Mail API quotas.
Table 2-5. App Engine Quotas for Mail API Resources
Mail API Calls
32 calls / min
8 recipients /
24 mails / min
9,700 mails /
Message Body Data
340KB / min
84MB / min
560 KB / min
300MB / min
This e-mail allocation is hefty, even for the free account. Let's take a deeper look into
each of these measurements to see how App Engine calculates them.
Mail API Calls : The total number of times the application accesses
the mail services to send an e-mail message.