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eMail: Ratelimit exponential backup for Amazon SES

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This commit is contained in:
Martin Gross
2022-04-19 10:39:33 +02:00
parent e9c440ceed
commit 1c4173a2ab
1 changed files with 5 additions and 2 deletions
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7
src/pretix/base/services/mail.py
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@@ -485,14 +485,17 @@ def mail_send_task(self, *args, to: List[str], subject: str, body: str, html: st
try:
backend.send_messages([email])
except (smtplib.SMTPResponseException, smtplib.SMTPSenderRefused) as e:
if e.smtp_code in (101, 111, 421, 422, 431, 432, 442, 447, 452):
if e.smtp_code == 432 and settings.HAS_REDIS:
if e.smtp_code in (101, 111, 421, 422, 431, 432, 442, 447, 452, 454):
if e.smtp_code in (432, 454) and settings.HAS_REDIS:
# This is likely Microsoft Exchange Online which has a pretty bad rate limit of max. 3 concurrent
# SMTP connections which is *easily* exceeded with many celery threads. Just retrying with exponential
# backoff won't be good enough if we have a lot of emails, instead we'll need to make sure our retry
# intervals scatter such that the email won't all be retried at the same time again and cause the
# same problem.
# See also https://docs.microsoft.com/en-us/exchange/troubleshoot/send-emails/smtp-submission-improvements
#
# Also observed on AWS SES with 454:
# https://aws.amazon.com/blogs/messaging-and-targeting/how-to-handle-a-throttling-maximum-sending-rate-exceeded-error/
from django_redis import get_redis_connection
redis_key = "pretix_mail_retry_" + hashlib.sha1(f"{getattr(backend, 'username', '_')}@{getattr(backend, 'host', '_')}".encode()).hexdigest()