LetterAgent

Mail physical letters by just asking your AI assistant.

Status: LetterAgent is currently in private testing ahead of public launch. Everything on this page describes the service as it works today.

Home > Guides > Return envelopes

Can I include a return envelope in a mailed letter?

Yes, slipping a pre-addressed, pre-stamped return envelope into your letter is standard practice when you want a reply. LetterAgent can't do this one: every job prints only your letter, no inserts, so the reply envelope has to go in at a post office. Business replies work differently, using a permit so the sender pays only on returned replies.

What is a SASE, and when is one expected?

SASE stands for self-addressed stamped envelope: an envelope addressed back to you, with a stamp on it, tucked inside your letter. It removes every excuse not to reply. Etiquette calls for a SASE when you're asking a favor of a stranger: requesting a signed photo, applying for something by mail, asking an author or researcher a question, submitting to a small publication. In each case you're imposing on the recipient's time and postage, so you pre-pay both.

One point of etiquette that trips people up: you do not send a SASE to a business you're in a normal commercial relationship with. Your landlord, your bank, your insurance company: replying to you is their cost of doing business. Sending them a stamped envelope reads as odd. The SASE is for favors, not for transactions.

How should the return envelope be prepared?

Address it to yourself exactly the way you'd want it to come back, and write your return address (the recipient's address) on it.
Affix a real stamp, not metered postage. Meter marks carry a date and expire; a Forever stamp works whenever the reply is finally written. This is the detail that separates a good SASE from a useless one.
Size it right. If the reply will be a few pages, use a larger envelope inside your outer envelope, or fold your envelope so it fits.
Mind the weight. A SASE is usually one ounce and needs one stamp, but if the expected reply is thick, add enough postage. A reply envelope with insufficient postage comes back to you postage-due or doesn't come at all.

What is the difference between a SASE and business reply mail?

	SASE	Business reply mail
Who pays for the reply	You, the original sender, upfront via the stamp	The business, but only for replies that actually come back
Setup	None: any envelope and stamp	A postal permit and printed reply envelopes with the official indicia
Unused replies	The stamp is spent whether or not anyone replies	Nothing is paid on replies that never come
Best for	Individuals asking favors or expecting a personal reply	Companies running surveys, remittance slips, or order forms at scale

Business reply mail is the permit system: the envelope the recipient gets carries a printed permit mark instead of a stamp, and the post office bills the business for each one that actually travels. That's why the separate guide on business reply mail covers the permit mechanics in detail.

Can I include a return envelope when mailing through LetterAgent?

No. LetterAgent prints and mails your letter exactly as quoted: 8.5x11 single-sided pages in a double-window envelope, with no inserts, flyers, or return envelopes. If your letter needs a SASE, the practical route is to mail the letter yourself from a post office so you can tuck the return envelope inside, or ask someone with a printer and stamps to assemble it for you.

Related guides

Ready to mail it? Send your letter with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and it is printed and mailed.

LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.

Need help? Ask your assistant: it can check a job's status any time. If it ever can't handle something: hello@getletteragent.com