Limitations with Trainmail

Trainmail is free for ordinary personal use, but it is not an unlimited bulk-mailing, automated account-farming, or permanent file-storage service. Practical limits protect delivery quality, shared infrastructure, and other users.

Message size, attachment size, sending frequency, active sessions, and mailbox storage can be limited. Some limits are adaptive and may become stricter when activity resembles spam, credential checking, automated registrations, or a compromised account.

Receiving servers can also reject a message for their own policy or size rules, even when Trainmail accepts it for delivery. Repeated abuse, unsolicited bulk mail, or attempts to bypass safeguards may result in temporary restrictions or account review.

Developer API limits are documented on the API page and may differ by key, permission, and endpoint. If you have a legitimate high-volume use case, contact support before building around an assumed limit.