With emails, it's very difficult to quantify how much is too much or how often is too often. We monitor all the blacklists and several major bulk sender reputation services (services that monitor bulk email traffic and assign ratings to senders) on a daily basis. It is clear that the more often an ISP, filtering service, or reputation service sees bulk email coming from a sender to a recipient, the more that sender begins to be viewed with a suspicious eye. Quite often, there’s been a blacklisting incident or drop in reputation score that was preceded by a surge in volume and/or frequency of mailings.
Some good practices to avoid a volume/frequency issue are:
- Pace your mailings. If you have two big monthly newsletters, don't send them both on the same day. Volume- and frequency-related drops in sender reputation seem to correct themselves after a 3-5 day "rest." We suggest this as a minimum interval between large mailings when possible.
- If you have a communication you must send to several lists on the same day, schedule them to send at intervals, so they're not all going out at the same time.
- If you have multiple eNotify users, try to have them coordinate with each other and stagger their mailings so everyone is not sending them all in the same day/week.
- If you have two announcements to send out to the same list, if possible, combine them into one mailing instead of doing two separate ones.