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These domains receiving our emails are rate-limiting us. The practice of rate-limiting is to combat spam messaging. If a service sees that they are receiving many emails from another domain, they will automatically bottleneck the sender because it is assumed that they are receiving a flood of spam messages.
Why now?
Over time, the amount number of emails has steadily increased. UConn sends much of this email to external domains, possibly many emails in a small timeframe (e.g. Listserv). At some point, we cross the thresh hold threshhold with a given domain and they institute throttling.
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