appengine.standard_python3.bundled-services.mail.wsgi.main_test: test_send_receive failed

[flaky-bot[bot]]

Note: #10485 was also for this test, but it was closed more than 10 days ago. So, I didn't mark it flaky.

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commit: 555b9d630d21c08c2e9cb94b1a53780f602290f0 buildURL: Build Status, Sponge status: failed