For the last few months, many mailers have had issues delivering to AOL associated to variations of “mtain-df04.r1000.mx.aol.com Service unavailable – try again later.” By definition, these are temporary errors, so they should be retried until you’re able to get through, right? Yes and no, many mailers are not seeing successful delivery by the time their systems expire the message; so they retry, bog down their systems, and never get the mail through.
This error is essentially telling you AOL’s systems are too bogged down at the moment to be able to process your message. So what should we do? Here are some things to try:
1. If the system can’t handle the mail right now, don’t force it. Pause the mail for 30 min, an hour, whatever, to try again later and see if they’re able to handle your request at that time.
2. Test time of day mailing to find at what time(s) AOL’s systems are less busy to allow your mail through (if you find multiple times, it’s probably worth testing to see which time of drop will deliver your messages to the users before they’re in their inbox daily)
3. Test lowering how much volume you’re pushing through at once. Instead of trying to drop it all in a matter of minutes, try to drag it out throughout the day so you aren’t causing the systems to slow down.
4. Tweak your time out settings. Not everyone’s systems are easily manipulated in this way, but if you’re able to, tell your system if you start to see these messages, retry for X amount of time, then pause for Y amount of time before trying again or expiring.
Essentially, the answer is test, test, test. Depending on each mailer’s systems and volumes, what works for one, may not work for another. If you’ve tried these things and are sick of having to test and fight with deliverability, you could always reach out to Adknowledge to set up a List Management agreement and have us manage the tests and fight the fight for you (click here for more info).
Note: while this was dedicated to AOL, most of these techniques work for all ISPs. If you’re pushing high volumes while everyone else is, and causing the ISPs systems to bog down, you’re going to hurt your deliverability. Note what error messages you’re getting, and treat them appropriately…just because it says “Temporary, try again later,” doesn’t mean you should keep pounding it for hours and hours at high volume without ever expiring the data. Sometimes it works out better if you back off a bit.
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